Kotlin: FirMetadataSource.File.files has been removed

In new versions, but not old versions, we want FirMetadataSource.File.fir
instead.

Author: igfoo

java/kotlin-extractor/src/main/kotlin/utils/versions/v_1_5_0/FirMetadataSourceFirFile.kt

@@ -0,0 +1 @@
+// Nothing to do

java/kotlin-extractor/src/main/kotlin/utils/versions/v_1_9_0-Beta/CommentExtractorLighterAST.kt

@@ -1,6 +1,7 @@
 package com.github.codeql.comments
 
 import com.github.codeql.*
+import com.github.codeql.utils.versions.*
 import com.intellij.lang.LighterASTNode
 import com.intellij.util.diff.FlyweightCapableTreeStructure
 import org.jetbrains.kotlin.fir.backend.FirMetadataSource
@@ -26,7 +27,7 @@ class CommentExtractorLighterAST(
     // Returns true if it extracted the comments; false otherwise.
     fun extract(): Boolean {
         val sourceElement =
-            (file.metadata as? FirMetadataSource.File)?.files?.elementAtOrNull(0)?.source
+            (file.metadata as? FirMetadataSource.File)?.firFile?.source
         val treeStructure = sourceElement?.treeStructure
         if (treeStructure == null) {
             return false

java/kotlin-extractor/src/main/kotlin/utils/versions/v_1_9_0-Beta/FirMetadataSourceFirFile.kt

@@ -0,0 +1,7 @@
+package com.github.codeql.utils.versions
+
+import org.jetbrains.kotlin.fir.backend.FirMetadataSource
+import org.jetbrains.kotlin.fir.declarations.FirFile
+
+val FirMetadataSource.File.firFile: FirFile?
+    get() = this.files.elementAtOrNull(0)

java/kotlin-extractor/src/main/kotlin/utils/versions/v_1_9_0-Beta/LinesOfCodeLighterAST.kt

@@ -1,5 +1,6 @@
 package com.github.codeql
 
+import com.github.codeql.utils.versions.*
 import com.intellij.lang.LighterASTNode
 import com.intellij.util.diff.FlyweightCapableTreeStructure
 import org.jetbrains.kotlin.KtSourceElement
@@ -14,7 +15,7 @@ class LinesOfCodeLighterAST(val logger: FileLogger, val tw: FileTrapWriter, val
 
     fun linesOfCodeInFile(id: Label<DbFile>): Boolean {
         val sourceElement =
-            (file.metadata as? FirMetadataSource.File)?.files?.elementAtOrNull(0)?.source
+            (file.metadata as? FirMetadataSource.File)?.firFile?.source
         if (sourceElement == null) {
             return false
         }

java/kotlin-extractor/src/main/kotlin/utils/versions/v_2_0_0-RC1/FirMetadataSourceFirFile.kt

@@ -0,0 +1,7 @@
+package com.github.codeql.utils.versions
+
+import org.jetbrains.kotlin.fir.backend.FirMetadataSource
+import org.jetbrains.kotlin.fir.declarations.FirFile
+
+val FirMetadataSource.File.firFile: FirFile?
+    get() = this.fir