Refactor `fast-colors` to support tsconfig with `noImplicitAny`, `strictNullChecks` and `strictPropertyInitialization`

[chrisdholt]

As part of #5303 we turned off @typescript-eslint/typedef globally as it was overwritten across multiple packages. As part of that, we turned on noImplicitAny, strictNullChecks, strictPropertyInitialization for all packages. Turning this on revealed several issues related to both tsconfig settings in fast-colors and so it was turned off explicitly for that package. The errors should be fixed and addressed as part of this issue and the code should be tested to ensure that there are no breaks or side effects of the change. This issue exists to track turning that back on and resolving the errors.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[imrishabh18]

Hey @chrisdholt! Is this issue still valid. I would like to contribute to this project, and would like to know the first few steps to resolve this issue.

[janechu]

The @microsoft/fast-colors package has been removed and deprecated.