osbuild: use bootc install to deploy the container

Instead of deploying the container to the tree then copy all the contents
to the disk image, use bootc to directly manage the installation to the
target filesystems.

Right now this requires to use the image as the buildroot so this
requires python (for osbuild). This is tracked in [1].

[1] bootc-dev/bootc#1410
Requires osbuild/osbuild#2149

Author: jbtrystram

build.sh

@@ -182,10 +182,10 @@ patch_osbuild() {
 
    ## To make it easier to apply patches we'll move around the osbuild
    ## code on the system first:
-   rmdir /usr/lib/osbuild/osbuild
-   mv /usr/lib/python3.13/site-packages/osbuild /usr/lib/osbuild/
-   mkdir /usr/lib/osbuild/tools
-   mv /usr/bin/osbuild-mpp /usr/lib/osbuild/tools/
+   # mdir /usr/lib/osbuild/osbuild
+   # mv /usr/lib/python3.13/site-packages/osbuild /usr/lib/osbuild/
+   # mkdir /usr/lib/osbuild/tools
+   # mv /usr/bin/osbuild-mpp /usr/lib/osbuild/tools/
 
    ## Now all the software is under the /usr/lib/osbuild dir and we can patch
    #cat foo.patch | patch -d /usr/lib/osbuild -p1

src/cmd-osbuild

@@ -397,6 +397,10 @@ main() {
     fi
 
     outdir=$(mktemp -p "${tmp_builddir}" -d)
+    # To get a shell in the osbuild supervin VM uncomment this.
+    # osbuild can be started with `bash tmp/build.<artifact>/cmd.sh`
+    # See comment about checkpoints in runvm-osbuild
+    # RUNVM_SHELL=1 \
     runvm_with_cache -- /usr/lib/coreos-assembler/runvm-osbuild                                         \
                 --config "${runvm_osbuild_config_json}"                                                 \
                 --mpp "/usr/lib/coreos-assembler/osbuild-manifests/coreos.osbuild.${basearch}.mpp.yaml" \