[FEATURE] build (and test?) release docker images on each PR

[rvolosatovs]

Is your feature request related to a problem? Please describe.
In #616 some changes were made to release pipeline and the only thing blocking actually building these images on each PR is the fact that the tagging functionality assumes that it's running on a tagged release, which is not the case (see TODO

wasmcloud-otp/.github/workflows/release.yml

Lines 281 to 286 in 0f97bf4

	# TODO: Build on PRs and pushes to main (but do not push)
	# This is currently blocked on the `app-version` computation, which only supports semver tags
	# E.g.:
	# ```
	# Error: buildx failed with: ERROR: invalid tag "wasmcloud.azurecr.io/wasmcloud_host:616/merge": invalid reference format
	# ```

)

Describe the solution you'd like
Fix the tagging logic, maybe only apply the "git tag" tags on tag builds? Would be cool to also run these resulting images, but that could be a follow-up

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. If this has been closed too eagerly, please feel free to tag a maintainer so we can keep working on the issue. Thank you for contributing to wasmCloud!