Integrate sbt into `setup-java` or create a new one called `setup-sbt` for better support for self-hosted runners :rocket:

Description: Seems that, currently, sbt is part of the github-provided virtual environments, and not in setup-java

Justification: Having sbt installed in the github.com-provided runners is a bit problematic for users of self-hosted runners as it causes false expectations for this setup-java action, given that sbt is actually something that needs java to function. Thus installation of it would make much more sense to happen in this action, or alternatively in another new one, called setup-sbt or setup-scala (actually, an action with this name already exists and depends on a not very stable project, called jabba, see https://github.com/olafurpg/setup-scala/issues/48 for more background on this)

I had previously opened: https://github.com/actions/starter-workflows/issues/1309 which I have now closed, to keep comms here exclusively.

Our current, in-house workaround is to use sdkman.io to install everything manually in our self-hosted runners.

Are you willing to submit a PR? Yes

[guizmaii]

@dimisjim sbt has been added to the by-default-installed softwares of the latest OS versions supported in Github Actions (see https://github.com/actions/virtual-environments#available-environments for the OS versions):

• macOS 11 (which is macos-latest): https://github.com/actions/virtual-environments/blob/main/images/macos/macos-11-Readme.md#project-management
• Windows Server 2019 (which is windows-latest): https://github.com/actions/virtual-environments/blob/main/images/win/Windows2019-Readme.md#project-management
• Ubuntu 20.04 (which is ubuntu-latest): https://github.com/actions/virtual-environments/blob/main/images/linux/Ubuntu2004-Readme.md#project-management

[dmitry-shibanov]

Hello everyone. The new version was released with sbt caching support.