stages/ostree.deploy: support an ostree input

This will allow a user to specify an input directly to the deploy
stage rather than requiring a ostree.pull stage to be called first.

Adding inputs will also be useful when we soon add support for
deploying from a container rather than just deploying from an existing
ostree commit in a repo.

test/data/manifests/fedora-ostree-image.json

@@ -1040,24 +1040,6 @@
         {
           "type": "org.osbuild.ostree.init-fs"
         },
-        {
-          "type": "org.osbuild.ostree.pull",
-          "options": {
-            "repo": "/ostree/repo",
-            "remote": "osbuild"
-          },
-          "inputs": {
-            "commits": {
-              "type": "org.osbuild.ostree",
-              "origin": "org.osbuild.pipeline",
-              "references": {
-                "name:ostree-commit": {
-                  "ref": "fedora/x86_64/osbuild"
-                }
-              }
-            }
-          }
-        },
         {
           "type": "org.osbuild.ostree.os-init",
           "options": {
@@ -1108,6 +1090,17 @@
               "systemd.journald.forward_to_console=1",
               "luks.uuid=aedd1eef-f24e-425e-a9f3-bb5a1c996a95"
             ]
+          },
+          "inputs": {
+            "commits": {
+              "type": "org.osbuild.ostree",
+              "origin": "org.osbuild.pipeline",
+              "references": {
+                "name:ostree-commit": {
+                  "ref": "fedora/x86_64/osbuild"
+                }
+              }
+            }
           }
         },
         {

test/data/manifests/fedora-ostree-image.mpp.yaml

@@ -40,17 +40,6 @@ pipelines:
     source-epoch: 1659397331
     stages:
       - type: org.osbuild.ostree.init-fs
-      - type: org.osbuild.ostree.pull
-        options:
-          repo: /ostree/repo
-          remote: osbuild
-        inputs:
-          commits:
-            type: org.osbuild.ostree
-            origin: org.osbuild.pipeline
-            references:
-              name:ostree-commit:
-                ref: fedora/x86_64/osbuild
       - type: org.osbuild.ostree.os-init
         options:
           osname: fedora
@@ -83,6 +72,13 @@ pipelines:
             - systemd.log_target=console
             - systemd.journald.forward_to_console=1
             - luks.uuid=aedd1eef-f24e-425e-a9f3-bb5a1c996a95
+        inputs:
+          commits:
+            type: org.osbuild.ostree
+            origin: org.osbuild.pipeline
+            references:
+              name:ostree-commit:
+                ref: fedora/x86_64/osbuild
       - type: org.osbuild.ostree.fillvar
         options:
           deployment: