Add test instructions and some tidying

[samuelallan72]

Description

Add instructions for manually testing the plugin on a devstack.

Also do some tidying of the repo, removing unused files, clarifying the license, and fixing some minor issues I discovered on the way.

Also add a pull request template to remind developers to do the manual testing, because there are no tests in CI (apart from the quality lints).

Supporting information

Private-ref: BB-10035

Test instructions

• View the rendered README.md and ./docs/manual-test-plan.md to check for formatting issues.
• Follow the test instructions and devstack installation instructions in the README and verify everything works as expected.
• Follow the playbook in ./docs/manual-test-plan.md and verify the instructions are clear, easy to follow, and work as expected.

Deadline

None

[Kelketek]

@samuelallan72 I went ahead and reviewed this since I knew @tecoholic would already have a setup with it working, but I wouldn't, so it would be a better test. I did find a few issues.

@tecoholic Since @samuelallan72 is out the rest of the week, if you happen to have free time (other tasks in this epic are higher priority) and can address the notes, feel free to do so and I'll do another review pass.

[samuelallan72]

@Kelketek @tecoholic

Since @samuelallan72 is out the rest of the week,

I'll be back tomorrow (Thursday); I just took today off. 😄 Of course if you have time @tecoholic , feel free to push any changes! :)

[Kelketek]

@samuelallan72 Whoops! I misread your message on Mattermost. Cool-- noted, and thanks!

[samuelallan72]

@Kelketek I addressed your review comments and made some general usability improvements to the manual tests. This is ready for another review pass. :) cc @tecoholic

[Kelketek]

👍

• I tested this: Migration tests and manual test plan
• I read through the code
• I checked for accessibility issues
• Includes documentation
• Added to the Code Drift project board (for backports)