[LL FIR] add getOrBuildFir for KtAnnotation

^KT-65780

analysis/low-level-api-fir/testData/getOrBuildFir/wholeDeclaration/fileAnnotation.txt

@@ -0,0 +1,10 @@
+KT element: KtAnnotation
+FIR element: null
+FIR source kind: null
+
+FIR element rendered:
+null
+
+FIR FILE:
+FILE: [ResolvedTo(BODY_RESOLVE)] fileAnnotation.kt
+    @FILE:R|kotlin/Suppress|[Types](names = vararg(String()))