Using generic updater for a single file that contains multiple component's versions

[awoimbee]

Related to #1857

Is your feature request related to a problem? Please describe.

I have a helm values.yaml which contains versions for multiple apps (because I have this master app that spawns workers).

From #1857 (comment)

Personally I want this feature to be able to do this:

myapps:
  app1:
    version: 1.2.3 # x-release-please-app1-version
    config: {}
  app2:
    version: 6.4.3 # x-release-please-app2-version
  app3: ...

So I guess I would put in release-please-config:

        {
          "type": "generic",
          "path": "/helm/mychart/values.yaml"
          "inline-update-regex": "x-release-please-app1-version"
        }

Notes:

• I have to use the generic updater because the yaml one removes comments (yaml updater removes quotes from strings #2195)
• This use-case would also be covered by release-please searching for x-release-please-version-${package_name}, without any extra config.

Describe the solution you'd like

Either be able to pass inline-update-regex or release-please, by default, should search for x-release-please-myapp-version.