logic: indexer command refactoring

* moved SystemHeaderSearchPaths and FramewordSeearchPaths of indexer cxx indexer commands to CompilerFlags section
* added SourceGroupTestSuite to test indexer command generation of all source groups
* removed "compile_commands.json" from gitignore, because a resource file for the tests has this name

bin/test/data/SourceGroupTestSuite/java_empty/input/src/foo/Bar.java

@@ -0,0 +1,5 @@
+package foo;
+
+class Bar implements FooBar
+{
+}

bin/test/data/SourceGroupTestSuite/java_empty/input/src/foo/Foo.java

@@ -0,0 +1,5 @@
+package foo;
+
+class Foo implements FooBar
+{
+}

bin/test/data/SourceGroupTestSuite/java_empty/input/src/foo/FooBar.java

@@ -0,0 +1,5 @@
+package foo;
+
+public interface FooBar
+{
+}

bin/test/data/SourceGroupTestSuite/java_empty/input/src/foo/Main.java

@@ -0,0 +1,8 @@
+package foo;
+
+public class Main
+{
+	public Foo m_foo;
+	public Bar m_bar;
+}
+