[tests] Return caret names from ExpressionMarkerProvider

Render caret names in resolve testData, so that we don't have to guess
the indices of the carets;
it makes the multi-caret testData less error-prone.

Relevant for KT-65152 and KT-62695

analysis/analysis-test-framework/tests/org/jetbrains/kotlin/analysis/test/framework/services/ExpressionMarkersSourceFilePreprocessor.kt

@@ -99,8 +99,8 @@ class ExpressionMarkerProvider : TestService {
             }
     }
 
-    fun getAllCaretsPositions(file: PsiFile): List<Int> {
-        return carets.getAllCaretsOffsets(file.name)
+    fun getAllCarets(file: PsiFile): List<CaretMarker> {
+        return carets.getAllCarets(file.name)
     }
 
     fun getSelectedRangeOrNull(file: PsiFile): TextRange? = selected[file.name]
@@ -261,6 +261,21 @@ class ExpressionMarkerProvider : TestService {
     }
 }
 
+data class CaretMarker(val tag: String, val offset: Int) {
+
+    /**
+     * Full render of this caret marker in the `<caret>` or `<caret_$tag>` form.
+     *
+     * @see ExpressionMarkersSourceFilePreprocessor.TAGS.CARET_REGEXP
+     */
+    val fullTag: String
+        get() = if (tag.isEmpty()) {
+            "<caret>"
+        } else {
+            "<caret_${tag}>"
+        }
+}
+
 private class CaretProvider {
     private val caretToFile = mutableMapOf<String, CaretsInFile>()
 
@@ -269,8 +284,8 @@ private class CaretProvider {
         return cartsInFile.getCaretOffsetByTag(caretTag)
     }
 
-    fun getAllCaretsOffsets(filename: String): List<Int> {
-        return caretToFile[filename]?.getAllCaretsOffsets().orEmpty()
+    fun getAllCarets(filename: String): List<CaretMarker> {
+        return caretToFile[filename]?.getAllCarets().orEmpty()
     }
 
     fun addCaret(filename: String, caretTag: String?, caretOffset: Int) {
@@ -285,8 +300,8 @@ private class CaretProvider {
             return carets[tag.orEmpty()]
         }
 
-        fun getAllCaretsOffsets(): List<Int> {
-            return carets.values.toList()
+        fun getAllCarets(): List<CaretMarker> {
+            return carets.map { (tag, offset) -> CaretMarker(tag, offset) }
         }
 
         fun addCaret(caretTag: String?, caretOffset: Int) {