[FIR Test] Migrate AbstractFirLoadCompiledKotlin to new test infrastructure

Also introduce two different modes for those tests:
- load metadata compiled with K1
- load metadata compiled with K2

compiler/testData/loadJava/compiledKotlin/fromLoadJava/objectMembers.fir.txt

@@ -0,0 +1,6 @@
+public final object SomeObject : R|kotlin/Any| {
+    public final fun test(a: R|kotlin/Int|): R|kotlin/Int|
+
+    private constructor(): R|test/SomeObject|
+
+}