Future-proofing, confluence documentation and unit test improvements

[PolarisAstrum-NHS]

Added features requested for future-proofing, additional checks in testing, and documenting testing evidence automatically on Confluence.
Restructured code to improve readability.
Increased unit test coverage, improved existing unit tests and added unit tests for new features implemented.

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This change is 

[pep8speaks]

Hello @PolarisAstrum-NHS! Thanks for opening this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file tests/test_compare_annotation.py:

Line 22:80: E501 line too long (85 > 79 characters)
Line 28:80: E501 line too long (157 > 79 characters)
Line 29:80: E501 line too long (179 > 79 characters)
Line 30:80: E501 line too long (219 > 79 characters)
Line 31:80: E501 line too long (196 > 79 characters)
Line 41:1: E122 continuation line missing indentation or outdented
Line 139:80: E501 line too long (82 > 79 characters)
Line 152:80: E501 line too long (112 > 79 characters)
Line 333:80: E501 line too long (82 > 79 characters)
Line 335:80: E501 line too long (84 > 79 characters)

• In the file tests/test_git_handler.py:

Line 9:1: E402 module level import not at top of file
Line 10:1: E402 module level import not at top of file

• In the file tests/test_make_vep_test_configs.py:

Line 32:80: E501 line too long (85 > 79 characters)

• In the file tests/test_progress_tracker.py:

Line 280:80: E501 line too long (85 > 79 characters)
Line 303:80: E501 line too long (80 > 79 characters)
Line 327:80: E501 line too long (88 > 79 characters)
Line 379:80: E501 line too long (117 > 79 characters)
Line 476:80: E501 line too long (80 > 79 characters)
Line 515:80: E501 line too long (80 > 79 characters)
Line 553:80: E501 line too long (80 > 79 characters)

• In the file tests/test_utils.py:

Line 337:80: E501 line too long (81 > 79 characters)
Line 338:80: E501 line too long (81 > 79 characters)
Line 339:80: E501 line too long (80 > 79 characters)
Line 384:80: E501 line too long (80 > 79 characters)
Line 392:80: E501 line too long (128 > 79 characters)
Line 393:80: E501 line too long (128 > 79 characters)
Line 394:80: E501 line too long (127 > 79 characters)

• In the file tests/test_vep_testing.py:

Line 9:1: E402 module level import not at top of file
Line 95:35: W291 trailing whitespace
Line 99:80: E501 line too long (83 > 79 characters)