feat(extras): Add scala support using nvim-metals (#1347)

* Add scala support using nvim-metals

nvim-metals:
https://github.com/scalameta/nvim-metals

minimal example configuration from their documentation:
https://github.com/scalameta/nvim-metals/discussions/39

* add treesitter syntax highlighting

lua/lazyvim/plugins/extras/lang/scala.lua

@@ -0,0 +1,74 @@
+-- NOTE: This setup does not define any lsp or dap specific key bindings
+-- It is recommended that the LazyVim extras dap-core is imported "lazyvim.plugins.extras.dap.core"
+-- If you like you can setup your own key bindings.
+-- For minimalistic setup have a look at https://github.com/scalameta/nvim-metals/discussions/39
+return {
+  {
+    "hrsh7th/nvim-cmp",
+    requires = {
+      { "hrsh7th/cmp-nvim-lsp" },
+      { "hrsh7th/cmp-vsnip" },
+      { "hrsh7th/vim-vsnip" },
+    },
+  },
+  {
+    "scalameta/nvim-metals",
+    dependencies = {
+      "nvim-lua/plenary.nvim",
+      "mfussenegger/nvim-dap",
+    },
+    ft = { "scala", "sbt", "java" },
+    init = function()
+      local metals_config = require("metals").bare_config()
+      metals_config.init_options.statusBarProvider = "on"
+      metals_config.settings = {
+        showImplicitArguments = true,
+        excludedPackages = { "akka.actor.typed.javadsl", "com.github.swagger.akka.javadsl" },
+      }
+      metals_config.capabilities = require("cmp_nvim_lsp").default_capabilities()
+      metals_config.on_attach = function(client, bufnr)
+        require("metals").setup_dap()
+      end
+
+      local nvim_metals_group = vim.api.nvim_create_augroup("nvim-metals", { clear = true })
+      vim.api.nvim_create_autocmd("FileType", {
+        -- NOTE: You may or may not want java included here. You will need it if you
+        -- want basic Java support but it may also conflict if you are using
+        -- something like nvim-jdtls which also works on a java filetype autocmd.
+        pattern = { "scala", "sbt", "java" },
+        callback = function()
+          require("metals").initialize_or_attach(metals_config)
+        end,
+        group = nvim_metals_group,
+      })
+
+      -- Debug settings
+      local dap = require("dap")
+      dap.configurations.scala = {
+        {
+          type = "scala",
+          request = "launch",
+          name = "RunOrTest",
+          metals = {
+            runType = "runOrTestFile",
+            --args = { "firstArg", "secondArg", "thirdArg" }, -- here just as an example
+          },
+        },
+        {
+          type = "scala",
+          request = "launch",
+          name = "Test Target",
+          metals = {
+            runType = "testTarget",
+          },
+        },
+      }
+    end,
+  },
+  {
+    "nvim-treesitter/nvim-treesitter",
+    opts = function(_, opts)
+      vim.list_extend(opts.ensure_installed, { "scala" })
+    end,
+  },
+}