feat: allow disabling auto review thread opening

[GuillaumeLagrange]

Describe what this PR does / why we need it

Add a config option to disable the auto thread opening on cursor move during review

Due to how diff works in nvim, I found it very hard to focus whenever there was more than one or two comments on a file

Does this pull request fix one issue?

Fixes #536

Describe how you did it

• Add the config option
• Create a command to call show review thread so that users can bind it
• When the config option is set,
  • do not create the cursor move autocmd that calls show review thread
  • create an local buffer keybind to close the comment buffer on q since it no longer auto closes when going back to diff

Describe how to verify it

Octo config

  opts = {
    reviews = {
      auto_show_threads = false,
    },
  },

Open a pr review

• Go on a thread, call <CMD>Octo review thread<CR>
  or
• Create a comment using <CMD>Octo comment add<CR>

See buffer open, and press q to close it

[pwntester]

Thanks @GuillaumeLagrange looks good to me and actually may use it myself 😄

[GuillaumeLagrange]

I have noticed a small regression that I believe this causes: if you open a comment from the left diff window (comment buffer opens on the right window), the diffthis is not properly applied to the right window on closing the comment buffer.

I'll open a PR with the fix

[GuillaumeLagrange]

I can't reproduce, it must have been a half baked local feature causing it, sorry for the useless ping