CMake build: Disable FakeVim and building with PCH with Qt 6

FakeVim does not compile on MSVC because Qt 6 doesn't like
meta types that are recursive maps with keys that have a custom
operator==.
Building with PCH has different issues on macOS and MSVC.

Change-Id: Id1b9580f7347f1c8facade67fd74532a023af41f
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>
Reviewed-by: hjk <hjk@qt.io>

src/plugins/fakevim/CMakeLists.txt

@@ -1,4 +1,5 @@
 add_qtc_plugin(FakeVim
+  CONDITION Qt5_VERSION VERSION_LESS 6.0.0
   PLUGIN_DEPENDS Core TextEditor
   PLUGIN_TEST_DEPENDS CppEditor CppTools
   SOURCES ${TEST_SOURCES}