feat(pack): add fish pack (#817)

* feat(pack): add fish pack

* fix(fish): Use mason-null-ls instead of none-ls

* Revert "fix(fish): Use mason-null-ls instead of none-ls"

This reverts commit 26232a1.

* fix(fish): add requirements in the README for fish pack

---------

Co-authored-by: Uzair Aftab <muaf@nmbu.no>

lua/astrocommunity/pack/fish/README.md

@@ -0,0 +1,11 @@
+# Elm Language Pack
+
+Requires the following in your `PATH`
+
+- [fish](https://github.com/fish-shell/fish-shell)
+
+This plugin pack does the following:
+
+- Adds `fish` Treesitter parser
+- Adds `fish_indent` formatter
+- Adds `fish` linter

lua/astrocommunity/pack/fish/init.lua

@@ -0,0 +1,41 @@
+return {
+  {
+    "nvim-treesitter/nvim-treesitter",
+    opts = function(_, opts)
+      if opts.ensure_installed ~= "all" then
+        opts.ensure_installed = require("astrocore").list_insert_unique(opts.ensure_installed, { "fish" })
+      end
+    end,
+  },
+  {
+    "nvimtools/none-ls.nvim",
+    optional = true,
+    opts = function(_, opts)
+      local nls = require "null-ls"
+      if type(opts.sources) == "table" then
+        opts.sources = vim.list_extend(opts.sources, {
+          nls.builtins.formatting.fish_indent,
+          nls.builtins.diagnostics.fish,
+        })
+      end
+    end,
+  },
+  {
+    "stevearc/conform.nvim",
+    optional = true,
+    opts = {
+      formatters_by_ft = {
+        fish = { "fish_indent" },
+      },
+    },
+  },
+  {
+    "mfussenegger/nvim-lint",
+    optional = true,
+    opts = {
+      linters_by_ft = {
+        fish = { "fish" },
+      },
+    },
+  },
+}