Add FIR resolve test (call extension from extension)

compiler/fir/resolve/testData/resolve/extension.kt

@@ -0,0 +1,5 @@
+fun String.foo() {}
+
+fun String.bar() {
+    foo()
+}

compiler/fir/resolve/testData/resolve/extension.txt

@@ -0,0 +1,6 @@
+FILE: extension.kt
+    public final fun R|kotlin/String|.foo(): R|kotlin/Unit| {
+    }
+    public final fun R|kotlin/String|.bar(): R|kotlin/Unit| {
+        <Unresolved name: foo>#()
+    }

compiler/fir/resolve/tests/org/jetbrains/kotlin/fir/FirResolveTestCaseGenerated.java

@@ -54,6 +54,11 @@ public class FirResolveTestCaseGenerated extends AbstractFirResolveTestCase {
         runTest("compiler/fir/resolve/testData/resolve/enum.kt");
     }
 
+    @TestMetadata("extension.kt")
+    public void testExtension() throws Exception {
+        runTest("compiler/fir/resolve/testData/resolve/extension.kt");
+    }
+
     @TestMetadata("F.kt")
     public void testF() throws Exception {
         runTest("compiler/fir/resolve/testData/resolve/F.kt");