Implement :map to allow the user to visualize the existing remaps

[berknam]

Implement :map and its multiple variants like :nm[ap], :im[ap], :vm[ap], :no[remap] :unm[ap], :nun[map], etc to check what keys are mapped to what.

Also implement a way of creating <buffer> only remaps using these commands. This requires having 'local' remaps per editor (document).

[sql-koala]

@berknam , are you a member now? (asking, because I see you added labels yourself; I saw that was offered to you).

[berknam]

@berknam , are you a member now? (asking, because I see you added labels yourself; I saw that was offered to you).

Yes I'm part of the team now! 😄 ❤️

BTW have you checked this PR #5842? It includes some fixes that should solve the issue #4075. If you have the time to test that PR and give your feedback I would really appreciate! 👍