[LL] add tests for FirDeclarationForCompiledElementSearcher

build stub if was not able to load:
expected that in IDE stubs would always be found in the index, for tests -
build from virtual file

analysis/low-level-api-fir/testdata/getOrBuildFirBinary/functionWithDefinitelyNotNullParameter.txt

@@ -0,0 +1,8 @@
+KT element: KtNamedFunction
+KT element text:
+public final fun <T> functionWithTAndAnyValue(otherVal: T & Any): kotlin.Unit { /* compiled code */ }
+FIR element: FirSimpleFunctionImpl
+FIR source kind: KtRealSourceElementKind
+
+FIR element rendered:
+public final [ResolvedTo(BODY_RESOLVE)] fun <[ResolvedTo(BODY_RESOLVE)] T> functionWithTAndAnyValue([ResolvedTo(BODY_RESOLVE)] otherVal: R|T & Any|): R|kotlin/Unit|