lsp4ij: Add support for Regal language server

[charlieegan3]

This PR uses the lsp4ij library to build in basic support for the Regal language server. I have generally worked on the server component and LSP clients are still a bit of a new thing for me.

For this work, I have as closely as possible followed the guide here - I found it to be very helpful.

Some things that are not perfect:

• lsp: Use full text replacement for Intellij fmt regal#1637 is needed to ensure that formatting works reliably (see videos below).
• Starting a debugging session works, but breakpoints are not respected and per-rule debugging is also not supported. I have tried, but wasn't able to get either of these working. I have left in RegalDebugAdapterDescriptor as it does work, but just not with the same features as other clients yet.

Examples of some functionality (./gradlew :plugin:runIde for testing)

Screen.Recording.2025-07-30.at.10.40.46.mov

Formatting issues (fixed in regal PR)

Screen.Recording.2025-07-29.at.16.21.54.mov

Screen.Recording.2025-07-30.at.10.01.08.mov

[charlieegan3]

Hey @vgramer, if you have any time to look this one over that'd be appreciated!

[angelozerr]

@charlieegan3 thanks so much for using LSP4IJ.

Please note that i am improving dap api to customize breakpoint type, configuration type, configuration settings editor, etc

If you install lsp4ij nighthy you qhould have rhose feature.

I need to write docs.

[angelozerr]

To improve your lsp and dap support, you should implement an lsp4ij installer for lsp and dap.

Please read doc at https://github.com/redhat-developer/lsp4ij/blob/main/docs%2FUserDefinedLanguageServerTemplate.md

[vgramer]

@charlieegan3 thanks for implementing lsp !

the "light" tests are failling because IDE create file in temp FS (IIRC in memory), which is not compatible with lsp. i think the simpler solution is to disable lsp adn dap for these tests.

all light test extends OpaTestBase.

import  com.redhat.devtools.lsp4ij.LanguageServerManager
import  com.redhat.devtools.lsp4ij.dap.DebugAdapterManager

abstract class OpaTestBase : BasePlatformTestCase(), OpaTestCase {
    override fun setUp() {
        super.setUp()
        
        // light tests use tempFS which is not compatible with lsp. So we need to disable it
        LanguageServerManager.getInstance(myFixture.project).stop("regal")

        val debugAdapterManager = DebugAdapterManager.getInstance()
        debugAdapterManager.getDebugAdapterServerById("regal-debug")
            ?.let { debugAdapterManager.removeDebugAdapterServer(it) }

    }
}

if we need lsp for testing, we can still use OpaWithRealProjectTestBase which creates a real project but is slower.

Another solution could be to disable lsp and dap programaticcaly in production by

• make RegalLanguageServerFactory to implement LanguageServerEnablementSupport
• ovverdie RegalDebugAdapterDescriptorFactory.isDebuggableFile to detect tempFS and return false� (this one seems a bit hacky)