Support Protobuf plugin by kanro

[devkanro]

This PR make buf plugin support the IntelliJ Protobuf Plugin by @devkanro, hereafter referred to as the Protobuf plugin.

The buf plugin previously only supported the Protobuf plugin provided by JetBrains, hereafter referred to as the official plugin.

This Protobuf plugin is more feature rich than the official plugin, please see the GitHub home page for details..

I make both the deps of official plugin and protobuf plugin be optional, the buf plugin will work fine with anyone for them.

Resolve

• Use buf.build to download and manage dependencies devkanro/intellij-protobuf-plugin#214

[CLAassistant]

All committers have signed the CLA.

[nicksnyder]

Thanks for the contribution! Relevant reviewers are on vacation so we can take a look after they are back. In the meantime, it looks like CI doesn't pass with this change.

[devkanro]

Currently, the IDEA test framework does not support configuring the missing optional plugin, so I did not update some tests in the protobuf plugin, and the current test plan remains unchanged (only testing when the official plugin is enabled).

• Support for testing missing optional Idea plugins JetBrains/intellij-platform-gradle-plugin#115

[devkanro]

@nicksnyder Could you approval the workflows to run the tests.

[nicksnyder]

There are some check warnings on this diff. You can see them inline when you view the PR diff or you can see the check output here: https://github.com/bufbuild/intellij-buf/actions/runs/7338528883

[devkanro]

@nicksnyder Could you approval the workflows to run the tests again.

[devkanro]

@pkwarren Plz approval the workflows to run the tests again.

[pkwarren]

Code changes look good. We're discussing this PR more internally as there are some ongoing changes in this area we're working on.

[Alfus]

FYI, we filed devkanro/intellij-protobuf-plugin#229 as a potental avenue for deeper integration.

[nicksnyder]

Thank you for contributing this!