FIR checker: report tailrec problems on the keyword

FE1.0 reports it on the declaration signature. This is not ideal so we
move it to the `tailrec` keyword in FIR.

compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt

@@ -821,8 +821,8 @@ object DIAGNOSTICS_LIST : DiagnosticList("FirErrors") {
         // TODO: replace with KtParameter
         val CANNOT_INFER_PARAMETER_TYPE by error<KtElement>()
 
-        val NO_TAIL_CALLS_FOUND by warning<KtNamedFunction>(PositioningStrategy.DECLARATION_SIGNATURE)
-        val TAILREC_ON_VIRTUAL_MEMBER_ERROR by error<KtNamedFunction>(PositioningStrategy.DECLARATION_SIGNATURE)
+        val NO_TAIL_CALLS_FOUND by warning<KtNamedFunction>(PositioningStrategy.TAILREC_MODIFIER)
+        val TAILREC_ON_VIRTUAL_MEMBER_ERROR by error<KtNamedFunction>(PositioningStrategy.TAILREC_MODIFIER)
         val NON_TAIL_RECURSIVE_CALL by warning<PsiElement>(PositioningStrategy.REFERENCED_NAME_BY_QUALIFIED)
         val TAIL_RECURSION_IN_TRY_IS_NOT_SUPPORTED by warning<PsiElement>(PositioningStrategy.REFERENCED_NAME_BY_QUALIFIED)
     }

compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/model/RegularDiagnosticData.kt

@@ -107,6 +107,7 @@ enum class PositioningStrategy(private val strategy: String? = null) {
     NON_FINAL_MODIFIER_OR_NAME,
     ENUM_MODIFIER,
     FIELD_KEYWORD,
+    TAILREC_MODIFIER,
 
     ;