Move plugins into core blockly repository

[rachel-fenichel]

This is a parent issue for moving plugins from the blockly-samples repository to the blockly repository.

At the end of the project:

• Plugin code will live in the blockly repository. Examples and codelabs will continue to live in blockly-samples.
• Plugins and core code will have locked version numbers.
• Plugins and core code will be released simultaneously.
• All packages will be published to npm under their current names.

The motivations for this project are:

• Reduce release overhead when updating core and plugins together.
• Reduce development overhead when updating core and plugins together.
• Move away from a development setup in blockly-samples that is poorly supported by our tooling.

This project is called monorepo internally.

Overall steps:

• [ ] google/blockly-samples#2134
• [ ] #7757
• [x] #7758
• [ ] #7759
• [ ] #7760
• [ ] #7761
• [ ] #7762
• [ ] #7763
• [ ] #7764
• [ ] #7765
• [ ] #7766
• [ ] #7767
• [ ] #7768
• [ ] #7769
• [ ] #7770
• [ ] #7771
• [ ] #7772
• [ ] #7773
• [ ] #7774
• [ ] #7775

Outstanding decisions we need to make:

• [ ] What to do with pull requests against core and samples during this process
• [ ] How to converge linting styles between core and plugins (follow-up)
• [ ] Process for cherry-picks
• [ ] Branch protection rules
• [ ] Whether/how to publish reference documentation for plugins (follow-up)

[Aarya01Patil]

@BeksOmega Hey I would love to solve this issue if this is available