SONARKT-628 Fix memory leak: RegexCache should be per file and not per project

Otherwise it retains ASTs of files with regular expressions till the
end of project analysis.

Author: Godin

sonar-kotlin-api/src/main/java/org/sonarsource/kotlin/api/frontend/KotlinTree.kt

@@ -29,8 +29,9 @@ import org.sonarsource.kotlin.api.reporting.KotlinTextRanges.textPointerAtOffset
 class KotlinTree(
     val psiFile: KtFile,
     val document: Document,
-    val regexCache: RegexCache,
-)
+) {
+    val regexCache = RegexCache()
+}
 
 data class KotlinSyntaxStructure(val ktFile: KtFile, val document: Document, val inputFile: InputFile) {
     companion object {

sonar-kotlin-api/src/main/java/org/sonarsource/kotlin/api/sensors/AbstractKotlinSensorExecuteContext.kt

@@ -100,14 +100,13 @@ abstract class AbstractKotlinSensorExecuteContext(
 
     fun analyzeFiles(): Boolean {
         try {
-            val regexCache = RegexCache()
             progressReport.start(filenames)
             kotlinFiles.filter {
                 !EMPTY_FILE_CONTENT_PATTERN.matches(it.inputFile.contents())
             }.forEach { (ktFile, doc, inputFile) ->
                 if (sensorContext.isCancelled) return false
                 val inputFileContext = InputFileContextImpl(sensorContext, inputFile, isInAndroidContext)
-                val tree = KotlinTree(ktFile, doc, regexCache)
+                val tree = KotlinTree(ktFile, doc)
 
                 measureDuration(inputFile.filename()) {
                     analyzeFile(inputFileContext, tree)

sonar-kotlin-test-api/src/main/java/org/sonarsource/kotlin/testapi/TestUtils.kt

@@ -39,5 +39,5 @@ fun kotlinTreeOf(content: String, environment: Environment, inputFile: InputFile
         listOf(virtualFile),
     )
     val (ktFile, document) = KotlinSyntaxStructure.of(content, environment, inputFile)
-    return KotlinTree(ktFile, document, RegexCache())
+    return KotlinTree(ktFile, document)
 }