[Analysis API] Test 'IGNORE_SELF' mode in context collector tests

Parent declarations of the file copy are typically unresolved in the
'IGNORE_SELF' mode, as the declaration designation contains declarations
from the original file.

analysis/low-level-api-fir/testData/contextCollector/extensionFunction.copy.txt

@@ -0,0 +1,27 @@
+Tower Data Context:
+    Element 0
+        Scope: FirDefaultStarImportingScope
+    Element 1
+        Scope: FirExplicitStarImportingScope
+    Element 2
+        Scope: FirDefaultSimpleImportingScope
+    Element 3
+        Scope: FirDefaultSimpleImportingScope
+    Element 4
+        Scope: FirPackageMemberScope
+    Element 5
+        Scope: FirExplicitSimpleImportingScope
+    Element 6
+        Scope: FirLocalScope
+    Element 7
+        Implicit receiver:
+            FirNamedFunctionSymbol public final fun R|kotlin/String|.test(): R|kotlin/Unit|
+                Type: kotlin.String
+    Element 8
+        Scope: FirLocalScope
+
+FILE: [ResolvedTo(IMPORTS)] extensionFunction.kt
+    public final [ResolvedTo(BODY_RESOLVE)] fun R|kotlin/String|.test(): R|kotlin/Unit| {
+        R|/consume|(this@R|/test|)
+    }
+    public? final? [ResolvedTo(RAW_FIR)] fun consume([ResolvedTo(RAW_FIR)] obj: Any): R|kotlin/Unit| { LAZY_BLOCK }