Transaction: Fail the resolve if xa.metadata invalid or missing

If we fail to parse xa.metadata from the summary cache or the commit
xa.metadata we fail the resolve.

If xa.metadata is missing in the commit we fail the resolve (it is
always set in the summary cache, because summary update converts
missing xa.metadata to "", so we either get that, or cache miss which
leads to resolving from the commit.

This means that op->resolved_metadata is always set during install and
updates, which means we will show the app permissions. The transaction
will also always make sure that this data actually matches what gets
deployed.

Before this change an invalid metadata in the summary cache could lead
to a NULL resolved_metadata, which means we wouldn't print the app
permissions, yet we would still deploy some metadata file that could
have permissions. (NOTE: It would fail to deploy unless the
xa.metadata in the commit matched the metadata file, but in this
corner case we would't compare the summary and commit metadata, so
they may differ.)