fix(rust): only use mason.nvim if it is present (#4963)

## Description

Fix the lang/rust extra for users that don't use mason. Uses the fix
suggested in
https://github.com/LazyVim/LazyVim/issues/4957#issuecomment-2521787846,
which works perfectly!

## Related Issue(s)

Fixes https://github.com/LazyVim/LazyVim/issues/4957

## Screenshots

n/a

## Checklist

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

Co-authored-by: Felix Rath <frath@cloudflare.com>

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

@@ -97,16 +97,18 @@ return {
       },
     },
     config = function(_, opts)
-      local package_path = require("mason-registry").get_package("codelldb"):get_install_path()
-      local codelldb = package_path .. "/extension/adapter/codelldb"
-      local library_path = package_path .. "/extension/lldb/lib/liblldb.dylib"
-      local uname = io.popen("uname"):read("*l")
-      if uname == "Linux" then
-        library_path = package_path .. "/extension/lldb/lib/liblldb.so"
+      if LazyVim.has("mason.nvim") then
+        local package_path = require("mason-registry").get_package("codelldb"):get_install_path()
+        local codelldb = package_path .. "/extension/adapter/codelldb"
+        local library_path = package_path .. "/extension/lldb/lib/liblldb.dylib"
+        local uname = io.popen("uname"):read("*l")
+        if uname == "Linux" then
+          library_path = package_path .. "/extension/lldb/lib/liblldb.so"
+        end
+        opts.dap = {
+          adapter = require("rustaceanvim.config").get_codelldb_adapter(codelldb, library_path),
+        }
       end
-      opts.dap = {
-        adapter = require("rustaceanvim.config").get_codelldb_adapter(codelldb, library_path),
-      }
       vim.g.rustaceanvim = vim.tbl_deep_extend("keep", vim.g.rustaceanvim or {}, opts or {})
       if vim.fn.executable("rust-analyzer") == 0 then
         LazyVim.error(