refactor(cli): cleanup parse_args.ts (#4189)

* initial commit

* fix typo

* rename negated capturing group

* update nested functions

* update

* simplify setNested

* update

* add parseBooleanValue

* update

* remove unknown  value type

* rename fns

* update

* Update parse_args.ts

Co-authored-by: Asher Gomez <ashersaupingomez@gmail.com>

* Update cli/parse_args.ts

Co-authored-by: Asher Gomez <ashersaupingomez@gmail.com>

* update

* revert to letters.entries()

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Co-authored-by: Asher Gomez <ashersaupingomez@gmail.com>