This is needed because after changing default language version to 2.0,
we still need to test many scenarios from this test in K1.
Move K1-specific tests to OldCompileKotlinAgainstCustomBinariesTest, and
K2-specific tests to FirCompileKotlinAgainstCustomBinariesTest.
Mute failing K2 tests via `muteForK2`. It will throw exception if the
muted test will suddenly start passing.
Alexander Udalov