feat(copilot): use blink-copilot as blink.cmp copilot source (#5551)

## Description

<!-- Describe the big picture of your changes to communicate to the
maintainers
  why we should accept this pull request. -->

After reviewing and fixing bugs in blink-cmp-copilot, I realized that
there is significant room for improvement in its codebase. So I created
a new copilot source `blink-copilot` for `blink.cmp` that introduces
many new features, enhanced performance, and official `copilot.vim`
backend support. (`copilot.lua` is supported by default)

The plugin has been starred by over 30 users, and it is growing faster
than blink-cmp-copilot. After more than two weeks of gathering feedback
and addressing bugs, the plugin has become very stable, and I believe
it’s time to share it with a broader audience.

`blink-copilot` register the kind `Copilot` by default, so there is no
need to do extra transforming on the completion items.

## Related Issue(s)

<!--
  If this PR fixes any issues, please link to the issue here.
  - Fixes #<issue_number>
-->

## Screenshots

<!-- Add screenshots of the changes if applicable. -->

## Checklist

- [x] I've read the
[CONTRIBUTING](https://github.com/LazyVim/LazyVim/blob/main/CONTRIBUTING.md)
guidelines.

lua/lazyvim/plugins/extras/ai/copilot.lua

@@ -98,15 +98,14 @@ return {
         {
           "saghen/blink.cmp",
           optional = true,
-          dependencies = { "giuxtaposition/blink-cmp-copilot" },
+          dependencies = { "fang2hou/blink-copilot" },
           opts = {
             sources = {
               default = { "copilot" },
               providers = {
                 copilot = {
                   name = "copilot",
-                  module = "blink-cmp-copilot",
-                  kind = "Copilot",
+                  module = "blink-copilot",
                   score_offset = 100,
                   async = true,
                 },