feat: Look for recipes in ./recipes/, build files in ./files/, and Containerfiles in ./containerfiles/ (#157)

Recipe files can now be put into their own directory `./recipes/`. This
directory is NEVER copied into the build so changes to a recipe will no
longer cause cache misses for builds. Here is an example of my build
changing the second to last module and only requiring the last 2 `RUN`
layers to be run again.

```
 => CACHED [stage-config 1/1] COPY ./config /config                                                                                                       0.0s
 => CACHED [stage-modules 1/2] COPY --from=ghcr.io/blue-build/modules:latest /modules /modules                                                            0.0s
 => CACHED [stage-modules 2/2] COPY ./modules /modules                                                                                                    0.0s
 => CACHED [stage-keys 1/1] COPY cosign.pub /keys/jp-desktop-gaming.pub                                                                                   0.0s
 => CACHED [stage-4  2/16] RUN --mount=type=bind,from=stage-keys,src=/keys,dst=/tmp/keys   mkdir -p /usr/etc/pki/containers/   && cp /tmp/keys/* /usr/et  0.0s
 => CACHED [stage-bins 1/3] COPY --from=gcr.io/projectsigstore/cosign /ko-app/cosign /bins/cosign                                                         0.0s
 => CACHED [stage-bins 2/3] COPY --from=docker.io/mikefarah/yq /usr/bin/yq /bins/yq                                                                       0.0s
 => CACHED [stage-bins 3/3] COPY --from=ghcr.io/blue-build/cli:main-installer /out/bluebuild /bins/bluebuild                                              0.0s
 => CACHED [stage-4  3/16] RUN --mount=type=bind,from=stage-bins,src=/bins,dst=/tmp/bins   mkdir -p /usr/bin/   && cp /tmp/bins/* /usr/bin/   && ostree   0.0s
 => CACHED [stage-4  4/16] RUN   --mount=type=tmpfs,target=/var   --mount=type=bind,from=stage-config,src=/config,dst=/tmp/config,rw   --mount=type=bind  0.0s
 => CACHED [stage-4  5/16] RUN   --mount=type=tmpfs,target=/var   --mount=type=bind,from=stage-config,src=/config,dst=/tmp/config,rw   --mount=type=bind  0.0s
 => CACHED [stage-4  6/16] RUN   --mount=type=tmpfs,target=/var   --mount=type=bind,from=stage-config,src=/config,dst=/tmp/config,rw   --mount=type=bind  0.0s
 => CACHED [stage-4  7/16] RUN   --mount=type=tmpfs,target=/var   --mount=type=bind,from=stage-config,src=/config,dst=/tmp/config,rw   --mount=type=bind  0.0s
 => CACHED [stage-4  8/16] RUN   --mount=type=tmpfs,target=/var   --mount=type=bind,from=stage-config,src=/config,dst=/tmp/config,rw   --mount=type=bind  0.0s
 => CACHED [stage-4  9/16] RUN   --mount=type=tmpfs,target=/var   --mount=type=bind,from=stage-config,src=/config,dst=/tmp/config,rw   --mount=type=bind  0.0s
 => CACHED [stage-4 10/16] RUN   --mount=type=tmpfs,target=/var   --mount=type=bind,from=stage-config,src=/config,dst=/tmp/config,rw   --mount=type=bind  0.0s
 => CACHED [stage-4 11/16] RUN   --mount=type=tmpfs,target=/var   --mount=type=bind,from=stage-config,src=/config,dst=/tmp/config,rw   --mount=type=bind  0.0s
 => CACHED [stage-4 12/16] RUN   --mount=type=tmpfs,target=/var   --mount=type=bind,from=stage-config,src=/config,dst=/tmp/config,rw   --mount=type=bind  0.0s
 => CACHED [stage-4 13/16] RUN   --mount=type=tmpfs,target=/var   --mount=type=bind,from=stage-config,src=/config,dst=/tmp/config,rw   --mount=type=bind  0.0s
 => CACHED [stage-4 14/16] RUN   --mount=type=tmpfs,target=/var   --mount=type=bind,from=stage-config,src=/config,dst=/tmp/config,rw   --mount=type=bind  0.0s
 => [stage-4 15/16] RUN   --mount=type=tmpfs,target=/var   --mount=type=bind,from=stage-config,src=/config,dst=/tmp/config,rw   --mount=type=bind,from=  33.4s
 => [stage-4 16/16] RUN   --mount=type=tmpfs,target=/var   --mount=type=bind,from=stage-config,src=/config,dst=/tmp/config,rw   --mount=type=bind,from=s  0.7s
```

Support was also added to put all build files into `./files/` instead of
`./config/`. This is an all or nothing operation, meaning if there
exists a directory of `files` then the `config` directory will be
completely ignored. Work will have to be done in
https://github.com/blue-build/modules to allow users to put their files
directly in `./files/` and not `./files/files` for the `files` module or
`./files/scripts` for the scripts module.

Support was also added to move the `./config/containerfiles/` directory
to the root of the project. Now the directories you can find in the root
of projects are:

```
files/
containerfiles/
recipes/
```

integration-tests/legacy-test-repo/config/recipe.yml

@@ -0,0 +1,44 @@
+name: cli/test-legacy
+description: This is my personal OS image.
+base-image: ghcr.io/ublue-os/silverblue-surface
+image-version: 39
+modules:
+  - from-file: akmods.yml
+
+  - type: files
+    files:
+      - usr: /usr
+
+  - type: script
+    scripts:
+      - example.sh
+
+  - type: rpm-ostree
+    repos:
+      - https://copr.fedorainfracloud.org/coprs/atim/starship/repo/fedora-%OS_VERSION%/atim-starship-fedora-%OS_VERSION%.repo
+    install:
+      - micro
+      - starship
+    remove:
+      - firefox
+      - firefox-langpacks
+
+  - type: default-flatpaks
+    notify: true
+    system:
+      install:
+        - org.mozilla.firefox
+        - org.gnome.Loupe
+        - one.ablaze.floorp//lightning
+      remove:
+        - org.gnome.eog
+
+  - type: signing
+
+  - type: test-module
+
+  - type: containerfile
+    containerfiles:
+      - labels
+    snippets:
+      - RUN echo "This is a snippet" && ostree container commit