feat(extras): rego language support (#4297)

It took a while, but finally we can work with
[OPA](https://www.openpolicyagent.org/) like a BOSS in neovim.

Linking some PR-s that had to land in the past couple of months to make
this config as
simple as it is now:

- treesitter commentstring support in
<https://github.com/JoosepAlviste/nvim-ts-context-commentstring/pull/108>
- regols support in nvim-lspconfig:
<https://github.com/neovim/nvim-lspconfig/pull/2721>
- regols support in mason-registry:
<https://github.com/mason-org/mason-registry/pull/4896>
- regols support in mason-lspconfig:
<https://github.com/williamboman/mason-lspconfig.nvim/pull/403>
- regal support in nvim-lspconfig:
<https://github.com/neovim/nvim-lspconfig/pull/3071>
- regal support in mason-registry:
<https://github.com/mason-org/mason-registry/pull/5717>
- regal support in mason-lspconfig:
<https://github.com/williamboman/mason-lspconfig.nvim/pull/426>

## Description

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

## Related Issue(s)

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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.

Signed-off-by: Zoltán Reegn <zoltan.reegn@gmail.com>

lua/lazyvim/plugins/extras/lang/rego.lua

@@ -0,0 +1,20 @@
+return {
+  recommended = {
+    ft = "rego",
+  },
+  {
+    "neovim/nvim-lspconfig",
+    opts = {
+      servers = {
+        regols = {},
+        regal = {},
+      },
+    },
+  },
+  {
+    "nvim-treesitter/nvim-treesitter",
+    opts = {
+      ensure_installed = { "rego" },
+    },
+  },
+}