build_torcx_store: store additional 'metaPackage' field in torcx manifest

The torcx_manifest.json file currently has a 'sourcePackage' field which is
extracted from the first runtime dependency of the torcx package ebuild. This
is a convention, and causes sourcePackage to hold 'app-emulation/docker' for
the 'app-torcx/docker' package. This does not carry enough information to be
able to figure out what other packages are part of the torcx package.

Store an additional field, 'metaPackage', in the manifest which contains the
name of the torcx package. With the right ebuild it is then possible to figure
out what other packages are part of a given torcx package. This can then be
used to add that information to the image packages list.

Signed-off-by: Jeremi Piotrowski <jpiotrowski@microsoft.com>

build_library/torcx_manifest.sh

@@ -30,6 +30,7 @@ function torcx_manifest::add_pkg() {
   pkg_hash="${1}"; shift
   cas_digest="${1}"; shift
   source_package="${1}"; shift
+  meta_package="${1}"; shift
   update_default="${1}"; shift
 
   local manifest=$(cat "${path}")
@@ -39,6 +40,7 @@ function torcx_manifest::add_pkg() {
   "hash": "${pkg_hash}",
   "casDigest": "${cas_digest}",
   "sourcePackage": "${source_package}",
+  "metaPackage": "${meta_package}",
   "locations": []
 }
 EOF

build_torcx_store

@@ -230,6 +230,7 @@ function torcx_package() {
             "sha512-${sha512sum}" \
             "${digest}" \
             "${source_pkg}" \
+            "${pkg}" \
             "${update_default}" \
             "${pkg_locations[@]}"
         )