Port osbuild/images v0.33.0 with dot-notation to composer

Update the osbuild/images to the version which introduces "dot notation"
for distro release versions.

 - Replace all uses of distroregistry by distrofactory.
 - Delete local version of reporegistry and use the one from the
   osbuild/images.
 - Weldr: unify `createWeldrAPI()` and `createWeldrAPI2()` into a single
   `createTestWeldrAPI()` function`.
 - store/fixture: rework fixtures to allow overriding the host distro
   name and host architecture name. A cleanup function to restore the
   host distro and arch names is always part of the fixture struct.
 - Delete `distro_mock` package, since it is no longer used.
 - Bump the required version of osbuild to 98, because the OSCAP
   customization is using the 'compress_results' stage option, which is
   not available in older versions of osbuild.

Signed-off-by: Tomáš Hozza <thozza@redhat.com>

vendor/github.com/opencontainers/selinux/pkg/pwalkdir/README.md

@@ -0,0 +1,54 @@
+## pwalkdir: parallel implementation of filepath.WalkDir
+
+This is a wrapper for [filepath.WalkDir](https://pkg.go.dev/path/filepath#WalkDir)
+which may speed it up by calling multiple callback functions (WalkDirFunc)
+in parallel, utilizing goroutines.
+
+By default, it utilizes 2\*runtime.NumCPU() goroutines for callbacks.
+This can be changed by using WalkN function which has the additional
+parameter, specifying the number of goroutines (concurrency).
+
+### pwalk vs pwalkdir
+
+This package is very similar to
+[pwalk](https://pkg.go.dev/github.com/opencontainers/selinux/pkg/pwalkdir),
+but utilizes `filepath.WalkDir` (added to Go 1.16), which does not call stat(2)
+on every entry and is therefore faster (up to 3x, depending on usage scenario).
+
+Users who are OK with requiring Go 1.16+ should switch to this
+implementation.
+
+### Caveats
+
+Please note the following limitations of this code:
+
+* Unlike filepath.WalkDir, the order of calls is non-deterministic;
+
+* Only primitive error handling is supported:
+
+  * fs.SkipDir is not supported;
+
+  * no errors are ever passed to WalkDirFunc;
+
+  * once any error is returned from any walkDirFunc instance, no more calls
+    to WalkDirFunc are made, and the error is returned to the caller of WalkDir;
+
+  * if more than one WalkDirFunc instance will return an error, only one
+    of such errors will be propagated to and returned by WalkDir, others
+    will be silently discarded.
+
+### Documentation
+
+For the official documentation, see
+https://pkg.go.dev/github.com/opencontainers/selinux/pkg/pwalkdir
+
+### Benchmarks
+
+For a WalkDirFunc that consists solely of the return statement, this
+implementation is about 15% slower than the standard library's
+filepath.WalkDir.
+
+Otherwise (if a WalkDirFunc is actually doing something) this is usually
+faster, except when the WalkDirN(..., 1) is used. Run `go test -bench .`
+to see how different operations can benefit from it, as well as how the
+level of paralellism affects the speed.