feat(treesitter): Add Tree-sitter plugin for navigating source

Some movements, selection, etc. from Vim, usually don't work properly
when trying to detect the start/end of functions/classes scope and other
languages symbols when, for instance, language blocks are not
curly-bracket-based.

This Tree-sitter plugin aims to solve those issues using the AST of the
source file.

.gitmodules

@@ -79,6 +79,11 @@
 	url = https://github.com/nvim-treesitter/nvim-treesitter.git
 	shallow = true
 	ignore = all
+[submodule "nvim/pack/misc/start/nvim-treesitter-textobjects"]
+	path = nvim/pack/misc/start/nvim-treesitter-textobjects
+	url = https://github.com/nvim-treesitter/nvim-treesitter-textobjects.git
+	shallow = true
+	ignore = all
 [submodule "vim/pack/misc/start/vim-gitgutter"]
 	path = vim/pack/misc/start/vim-gitgutter
 	url = https://github.com/airblade/vim-gitgutter.git

nvim/lua/treesitter.lua

@@ -3,4 +3,19 @@ require'nvim-treesitter.configs'.setup {
   highlight = { enable = true },
   incremental_selection = { enable = true },
   indent = { enable = true },
+
+  -- textobjects treesitter plugin
+  textobjects = {
+    select = {
+      enable = true,
+      lookahead = true,
+      keymaps = {
+        ["af"] = "@function.outer",
+        ["if"] = "@function.inner",
+        ["ac"] = "@class.outer",
+        ["ic"] = { query = "@class.inner", desc = "Select inner part of a class region" },
+        ["as"] = { query = "@scope", query_group = "locals", desc = "Select language scope" },
+      },
+    },
+  },
 }

nvim/pack/misc/start/nvim-treesitter-textobjects

@@ -0,0 +1 @@
+Subproject commit 67ac27f859ee3f7584f3edef81d0942bb61d5344