[android] add gradle tasks for bundling js and assets in template

[foghina]

This adds gradle tasks that call react-native bundle with the correct args to bundle dev/release JS and assets. The dev task is disabled by default, as in dev mode people only use reload JS in most cases.

Submitting this as a pull request to have community visibility, although we have this code internally as well now and this will require an import.

Test Plan

• generate a project with react-native init, add some assets, run ./gradlew assembleRelease, sign & zipalign generated APK, run it -> works
• enable dev bundling task, run ./gradlew installDebug (not react-native run-android so as to not start the packager) -> works

CC:

• @martinbigio please approve of my use of react-native bundle
• @mkonicek for gradle tasks / config api
• @kmagiera I think you worked more extensively with gradle before
• @frantic for visibility

[facebook-github-bot]

By analyzing the blame information on this pull request, we identified @mkonicek and @foghina to be potential reviewers.

[martinbigio]

@foghina this is fine to me as it only adds new templates. Most likely I'll move the templates inside private-cli soon. Also, note that local-cli is now checked in on our repo, so now need to submit PR for this type of changes anymore :).

[foghina]

@martinbigio from the PR summary:

Submitting this as a pull request to have community visibility, although we have this code internally as well now and this will require an import.

:)

And yes, it only adds templates but these define how people will use react-native bundle as part of the gradle build on Android.

[foghina]

@facebook-github-bot shipit

[facebook-github-bot]

@foghina updated the pull request.

[foghina]

This got imported in 9dc036d, not sure why the bot hasn't closed it.