[UV-K5] add option to disable TX on channel and add UV-K5(8) as an alias for UV-K5

[sq5bpf]

CHIRP PR Checklist

The following must be true before PRs can be merged:

• All tests must be passing.
• Commits should be squashed into logical units.
• Commits should be rebased (or simply rebase-able in the web UI) on current master. Do not put merge commits in a PR.
• Commits in a single PR should be related.
• Major new features or bug fixes should reference a CHIRP issue.
• New drivers should be accompanied by a test image in tests/images (except for thin aliases where the driver is sufficiently tested already).
• All files must be GPLv3 licensed or contain no license verbiage. No additional restrictions can be placed on the usage (i.e. such as noncommercial).

Please also follow these guidelines:

• Keep cleanups in separate commits from functional changes.
• Please write a reasonable commit message, especially if making some change that isn't totally obvious (such as adding a new model, adding a feature, etc).
• Do not add new py2-compatibility code (No new uses of six, future, etc).
• All new drivers should set NEEDS_COMPAT_SERIAL=False and use MemoryMapBytes.
• New drivers and radio models will affect the Python3 test matrix. You should regenerate this file with tox -emakesupported and include it in your commit.

[kk7ds]

I just pushed a change to fix your commit message to reference the bug. In the future, please add this to the commit message:

Fixes: #10702

That way the issue tracker will reference the commit and automatically resolve the bug.

Also, it makes my life so much easier if you use topic branches instead of your own master when I have to push a fix like this... :)