Added abstract MakeColor and CreateColors to create the colors at once.

[BDisp]

Per #666 - It has long wanted to do this to change the colors in one place for all drivers. I didn't named this PR in the form of "Fixes" because could have another refactors to remove duplicate code, but this one was very significant.

Pull Request checklist:

• I've named my PR in the form of "Fixes #issue. Terse description."
• My code follows the style guidelines of Terminal.Gui - if you use Visual Studio, hit CTRL-K-D to automatically reformat your files before committing.
• My code follows the Terminal.Gui library design guidelines
• I ran dotnet test before commit
• I have made corresponding changes to the API documentation (using /// style comments)
• My changes generate no new warnings
• I have checked my code and corrected any poor grammar or misspellings
• I conducted basic QA to assure all features are working

[BDisp]

Toplevel Color Scheme:

Base Color Scheme:

Dialog Color Scheme:

Menu Color Scheme:

Error Color Scheme:

[tig]

Can you delete the old, commented out code?

[BDisp]

Can you delete the old, commented out code?

Done. Thanks.