feat(jj): Add lazyjj

[Cretezy]

📑 Description

• Adds lazyjj (a TUI for jj, similar to lazygit) mapping

Disclamer: I am the author of lazyjj.

[github-actions]

Review Checklist

Does this PR follow the [Contribution Guidelines](development guidelines)? Following is a partial checklist:

Proper conventional commit scoping:

• If you are adding a new plugin, the scope would be the name of the category it is being added into. ex. feat(utility): added noice.nvim plugin

• If you are modifying a pre-existing plugin or pack, the scope would be the name of the plugin folder. ex. fix(noice-nvim): fix LSP handler error

• Pull request title has the appropriate conventional commit type and scope where the scope is the name of the pre-existing directory in the project as described above

• README is properly formatted and uses fenced in links with <url> unless they are inside a [title](url)

• Proper usage of opts table rather than setting things up with the config function.

[Uzaaft]

You should add a requirement about lazyjj being in path.
Or actually, we should make it an optional dependency. Similar to how lazygit is today.

[Cretezy]

@Uzaaft: How should that work? Should it not include the key mapping if lazyjj is not present, or should it show an error when it's executed?

For lazygit, AstroNvim doesn't add the mapping if it's not in the path. I'm inclined to do the same.

[Uzaaft]

That was my point, I should have written it better. Lets go for the same approach as how astronvim does it today with lazygit.