[tests] Refactor AbstractReferenceResolveTest. Part 1

Instead of relying on UNRESOLVED_REFERENCE directive for the whole file,
just render the unresolved reference right in the .txt testdata

This will allow to introduce multi-caret resolve testdata more naturally

Required for KT-65152 and KT-62695

analysis/analysis-api/testData/referenceResolve/kotlinPackage/kotlinPackageNotAllowed.kt

@@ -1,6 +1,5 @@
 // FE1.0 can resolve to `kotlin` package when it's not allowed
 // IGNORE_FE10
-// UNRESOLVED_REFERENCE
 // COMPILATION_ERRORS
 // FILE: a.kt
 package kotlin.pckg

analysis/analysis-api/testData/referenceResolve/kotlinPackage/kotlinPackageNotAllowed.txt

@@ -0,0 +1,2 @@
+Resolved to:
+Nothing (Unresolved reference)