t4207: modernize test
Before adding new tests to t4207-log-decoration-colors.sh, update the existing test to use modern test conventions. This includes: 1. Use lowercase in test names. 2. Keep all test setup inside the test_expect_success blocks. We need to be careful about left whitespace in the broken lines of the input file. 3. Do not use 'git' commands on the left side of a pipe. 4. Create a cmp_filtered_decorations helper to perform the 'log', 'sed', and test_decode_color manipulations. Move the '--all' option to be an argument so we can change that value in future tests. 5. Modify the 'sed' command to use a simpler form that is more portable. The next change will introduce new tests usinge these new conventions. Signed-off-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>