feat(extras): enable crates.nvim in-process lsp server (#4684)

## Description

Rather than manually handling hover and completions through nvim-cmp and
nvim-lspconfig, enable the crates.nvim in-process lsp server. This also
allows crates.nvim to provide code actions.

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maintainers
  why we should accept this pull request. -->

## Related Issue(s)

This change also removes the direct dependency on nvim-cmp, which should
help with #4680

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

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## Checklist

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

Co-authored-by: Folke Lemaitre <folke.lemaitre@gmail.com>

lua/lazyvim/plugins/extras/lang/rust.lua

@@ -6,26 +6,23 @@ return {
     })
   end,
 
-  -- Extend auto completion
+  -- LSP for Cargo.toml
   {
-    "hrsh7th/nvim-cmp",
-    optional = true,
-    dependencies = {
-      {
-        "Saecki/crates.nvim",
-        event = { "BufRead Cargo.toml" },
-        opts = {
-          completion = {
-            cmp = { enabled = true },
-          },
+    "Saecki/crates.nvim",
+    event = { "BufRead Cargo.toml" },
+    opts = {
+      completion = {
+        crates = {
+          enabled = true,
         },
       },
+      lsp = {
+        enabled = true,
+        actions = true,
+        completion = true,
+        hover = true,
+      },
     },
-    ---@param opts cmp.ConfigSchema
-    opts = function(_, opts)
-      opts.sources = opts.sources or {}
-      table.insert(opts.sources, { name = "crates" })
-    end,
   },
 
   -- Add Rust & related to treesitter
@@ -96,21 +93,6 @@ return {
     opts = {
       servers = {
         rust_analyzer = { enabled = false },
-        taplo = {
-          keys = {
-            {
-              "K",
-              function()
-                if vim.fn.expand("%:t") == "Cargo.toml" and require("crates").popup_available() then
-                  require("crates").show_popup()
-                else
-                  vim.lsp.buf.hover()
-                end
-              end,
-              desc = "Show Crate Documentation",
-            },
-          },
-        },
       },
     },
   },