New MPP highlighting test: check also line markers (KT-27494)

We have to do complex operations with tags, because otherwise
tags in different files prevent correct analysis of the current one

idea/testData/gradle/newMultiplatformHighlighting/first/src/commonMain/kotlin/My.kt

@@ -1,3 +1,3 @@
-expect class <error descr="[NO_ACTUAL_FOR_EXPECT] Expected class 'My' has no actual declaration in module first_jsMain for JS">My</error> {
-    fun foo()
+expect class <error descr="[NO_ACTUAL_FOR_EXPECT] Expected class 'My' has no actual declaration in module first_jsMain for JS"><lineMarker>My</lineMarker></error> {
+    fun <lineMarker>foo</lineMarker>()
 }

idea/testData/gradle/newMultiplatformHighlighting/first/src/jvmMain/kotlin/My.kt

@@ -1,5 +1,5 @@
-actual class My {
-    actual fun foo() {}
+actual class <lineMarker>My</lineMarker> {
+    actual fun <lineMarker>foo</lineMarker>() {}
 
     actual fun <error descr="[ACTUAL_WITHOUT_EXPECT] Actual function 'bar' has no corresponding expected declaration">bar</error>() {}
 }