KT-60957 [Analysis API] Properly handle source PSI for implicit invoke calls in KtFirReferenceShortener

For implicit invoke operator calls, there are two instances of
`FirResolvedNamedReference`. One of them references `invoke` function
and cannot be used to analyze the property access, and the second one
has `source == null`. Luckily, the parent of the second reference is
`FirPropertyAccessExpression`, which has the correct source

^KT-60957 Fixed

analysis/analysis-api/testData/components/referenceShortener/referenceShortener/variable_invokeOperator.kt

@@ -0,0 +1,15 @@
+// FILE: main.kt
+package test
+
+fun usage() {
+    <expr>dependency.foo()</expr>
+}
+
+// FILE: dependency.kt
+package dependency
+
+var foo: Foo = Foo()
+
+class Foo {
+    operator fun invoke() {}
+}

analysis/analysis-api/testData/components/referenceShortener/referenceShortener/variable_invokeOperator.txt

@@ -0,0 +1,7 @@
+Before shortening: dependency.foo()
+with DO_NOT_SHORTEN:
+with SHORTEN_IF_ALREADY_IMPORTED:
+with SHORTEN_AND_IMPORT:
+[qualifier] dependency.foo()
+with SHORTEN_AND_STAR_IMPORT:
+[qualifier] dependency.foo()