feat(lang): julia support (#6231)

## Description

- Another take on #4436.
- Adds LSP
- Adds cmp and blink.cmp for LaTeX symbols

## Related Issue(s)

#5455 

## Screenshots

![CleanShot 2025-07-05 at 08 05
01@2x](https://github.com/user-attachments/assets/36a6e5ac-2632-4a33-af9e-674b7f1b750d)

## Checklist

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

lua/lazyvim/plugins/extras/lang/julia.lua

@@ -0,0 +1,66 @@
+return {
+  recommended = function()
+    return LazyVim.extras.wants({
+      ft = { "julia" },
+      root = { "Project.toml" },
+    })
+  end,
+
+  {
+    "nvim-treesitter/nvim-treesitter",
+    opts = { ensure_installed = { "julia" } },
+  },
+
+  {
+    "neovim/nvim-lspconfig",
+    opts = {
+      servers = {
+        julials = {
+          settings = {
+            -- use the same default settings as the Julia VS Code extension
+            julia = {
+              completionmode = "qualify",
+              lint = { missingrefs = "none" },
+            },
+          },
+        },
+      },
+    },
+  },
+
+  -- cmp integration
+  {
+    "hrsh7th/nvim-cmp",
+    optional = true,
+    dependencies = { "kdheepak/cmp-latex-symbols" },
+    opts = function(_, opts)
+      table.insert(opts.sources, {
+        name = "latex_symbols",
+        option = {
+          strategy = 0, -- mixed
+        },
+      })
+    end,
+  },
+
+  -- blink.cmp integration
+  {
+    "saghen/blink.cmp",
+    optional = true,
+    dependencies = { "kdheepak/cmp-latex-symbols", "saghen/blink.compat" },
+    opts = {
+      sources = {
+        compat = { "latex_symbols" },
+        providers = {
+          latex_symbols = {
+            kind = "LatexSymbols",
+            async = true,
+            opts = {
+              strategy = 0, -- mixed
+            },
+          },
+        },
+      },
+    },
+  },
+}