legacy tests: migrate test35. #1318

Migrate vim's integration test 35 (increment/decrement commands) to
lua/busted.
legacy tests: migrate test4
legacy tests: migrate test102
legacy tests: migrate test9
legacy tests: migrate test22
legacy tests: migrate test106
legacy tests: migrate test18
legacy tests: migrate test_options
legacy tests: migrate test_insertcount
legacy tests: migrate test_utf8
legacy tests: migrate test81
legacy tests: migrate test_changelist
legacy tests: migrate test_autoformat_join