chore: move plugin stuff back into separate subproject

Putting it in the root project breaks the devkit plugin

build.gradle.kts

@@ -38,9 +38,11 @@ val clionVersion = properties("clionVersion").get()
 val clionPlugins = listOf("com.intellij.clion", "com.intellij.cidr.lang", "com.intellij.cidr.base", "com.intellij.nativeDebug")
 
 val lsp4jVersion = "0.21.1"
-val lsp4ijVersion = "0.0.2"
+val lsp4ijVersion = "0.3.0-20240702-174041"
 
-val lsp4ijDepString = "${if (lsp4ijVersion.contains("-")) "nightly." else ""}com.jetbrains.plugins:com.redhat.devtools.lsp4ij:$lsp4ijVersion"
+val lsp4ijNightly = lsp4ijVersion.contains("-")
+val lsp4ijDepString = "${if (lsp4ijNightly) "nightly." else ""}com.jetbrains.plugins:com.redhat.devtools.lsp4ij:$lsp4ijVersion"
+val lsp4ijPluginString = "com.redhat.devtools.lsp4ij:$lsp4ijVersion${if (lsp4ijNightly) "@nightly" else ""}"
 
 val lsp4ijDep: DependencyHandler.() -> Unit = {
     intellijPlatformPluginDependency(lsp4ijDepString)
@@ -138,7 +140,6 @@ allprojects {
                 dependsOn("generateGrammars")
             }
         }
-
     }
 
     configure<JavaPluginExtension> {
@@ -187,6 +188,9 @@ project(":zig") {
     dependencies {
         implementation(project(":common"))
         lsp4ijDep()
+        intellijPlatform {
+            plugin(lsp4ijPluginString)
+        }
     }
     tasks {
         generateLexer {
@@ -246,7 +250,9 @@ project(":zon") {
     }
 }
 
+project(":plugin") {
     dependencies {
+        implementation(project(":common"))
         implementation(project(":zig"))
         implementation(project(":project"))
         implementation(project(":zon"))
@@ -254,11 +260,7 @@ dependencies {
         intellijPlatform {
             zipSigner()
             pluginVerifier()
-        when (baseIDE) {
-            "idea" -> intellijIdeaCommunity(ideaVersion)
-            "clion" -> clion(clionVersion)
-        }
-        plugin("com.redhat.devtools.lsp4ij:$lsp4ijVersion")
+            plugin(lsp4ijPluginString)
         }
     }
 
@@ -370,16 +372,27 @@ tasks {
         buildPlugin {
             enabled = true
         }
+    }
+}
 
+tasks {
     generateLexer {
         enabled = false
     }
-
     generateParser {
         enabled = false
     }
 }
 
+dependencies {
+    intellijPlatform {
+        when (baseIDE) {
+            "idea" -> intellijIdeaCommunity(ideaVersion)
+            "clion" -> clion(clionVersion)
+        }
+    }
+}
+
 fun distFile(it: String) = layout.buildDirectory.file("dist/ZigBrains-${pluginVersion().get()}-$it-signed.zip")
 
 publishVersions.forEach {