feat: support for snacks.nvim picker

[roycrippen4]

Checklist

• Used only camelCase variable names.
• If functionality is added or modified, also made respective changes to the
  README.md (the .txt file is auto-generated and does not need to be modified).

Configuration

I chose not to expose snacks configuration options through the nvim-scissors config. It's possible to style the picker entirely through the snacks configuration. This information is mentioned in the README. I also chose not to implement the addSnippet function for snacks. Similar to dressing.nvim, snacks overrides vim.ui.select and can be modified through the snacks configuration.

Default snacks and nvim-scissors settings

Modified snacks settings w/ default nvim-scissors settings

Considerations

There is an edge case where a user could have both telescope and snacks installed. Right now telescope gets used since it's the first condition checked. It might make sense to add a configuration option to let the user pick their preferred picker. A simple string literal union of ---@type "telescope"|"snacks" would solve that issue.

[roycrippen4]

Closes #32

[chrisgrieser]

Thanks for the clean PR. Looks good to me.

Could you address the two failing checks? Apparently only markdown formatting and type annotation issues. Then I can merge.

[roycrippen4]

Just fixed the markdown issue. Snacks makes itself available through _G.Snacks which is part of why the type checking failed. Do you think using require("snacks").picker will fix the type checking?

[chrisgrieser]

Thx!