Add Haskell support (#5281) (#6786)

This PR adds the Haskell tree-sitter grammar copied from
[`nvim-treesitter`](https://github.com/nvim-treesitter/nvim-treesitter/tree/master/queries/haskell).
It also adds the Haskell Language Server.

This is a joint effort by myself (adding the grammar) and @leifu1128
(who is adding the language server integration).

This PR resolves https://github.com/zed-industries/zed/issues/5281

Release Notes:

- Added Haskell support
([#5281](https://github.com/zed-industries/zed/issues/5281)).