[FIR-TEST] Move analysis tests to separate module

compiler/fir/analysis-tests/testData/resolve/extension.kt

@@ -0,0 +1,13 @@
+fun String.foo() {}
+
+fun String.bar() {
+    foo()
+}
+
+class My {
+    fun bar() {
+        foo()
+    }
+}
+
+fun My.foo() {}