Line exclude regex just for keyword detector

[KevinHock]

In #127 we added a line exclude for all plugins and reverted 15a6e6a, which was a line exclude regex for just the high-entropy plugins, this was partially due to imagined use-cases of things someone may want to exclude from all plugins e.g. lines whose first non-whitespace character is a#, and general cleanliness (DRY).

The keyword detector however, is a young plugin with kind of an ambitious goal, and users shouldn't have to add to the FALSE_POSITIVES dict things that may be specific to their codebases, and version bumps won't need to happen to trim false positives.

This is a good-first-issue, b/c it was done very similarly in 15a6e6a

[hpandeycodeit]

@KevinHock I would like to work on this.

[KevinHock]

Awesome @hpandeycodeit, let me know if you need any help 👍

[hpandeycodeit]

@KevinHock Are we looking to change the same files as in this commit 15a6e6a

[KevinHock]

@hpandeycodeit We will still change detect_secrets/core/usage.py and tests/core/usage_test.py, except instead of changing HexHighEntropyString and Base64HighEntropyString we can change KeywordDetector to have the option. e.g. Instead of an _add_high_entropy_excludes function we can add something like a _add_keyword_exclude function that adds a --keyword-exclude option to the KeywordDetector.

Instead of the detect_secrets/plugins/high_entropy_strings.py and tests/plugins/high_entropy_strings_test.py files. We can change detect_secrets/plugins/keyword.py and tests/plugins/keyword_test.py
e.g. in keyword.py we can add an __init__ method to take in a new arg, then call super's init method. We can use the new arg to skip strings in the analyze_string_content method.

Hope this helps 👍 Let me know if you need me to clarify anything

[hpandeycodeit]

@KevinHock Thanks for the clarification. I created a PR. Let me know what you think.

[KevinHock]

Awesome, thank you @hpandeycodeit 👍

[KevinHock]

Closing as fixed by #132