feat/refacto: add configs.lua, setup install

- configs.lua holds the `repositories` data
- install health moved to health.lua
- plugins loads _root.setup() on startup
- install and list command are available through vim
> use them with `:TSInstall lang` and `:TSInstallInfo`

lua/nvim-treesitter/health.lua

@@ -1,8 +1,9 @@
 local api = vim.api
+local fn = vim.fn
 
-local install = require'nvim-treesitter.install'
 local queries = require'nvim-treesitter.query'
 local locals = require'nvim-treesitter.locals'
+local configs = require'nvim-treesitter.configs'
 
 local health_start = vim.fn["health#report_start"]
 local health_ok = vim.fn['health#report_ok']
@@ -12,15 +13,36 @@ local health_error = vim.fn['health#report_error']
 
 local M = {}
 
+local function configs_health()
+  if fn.executable('git') == 0 then
+    health_error('`git` executable not found.', {
+        'Install it with your package manager.',
+        'Check that your `$PATH` is set correctly.'
+      })
+  else
+    health_ok('`git` executable found.')
+  end
+
+  if fn.executable('cc') == 0 then
+    health_error('`cc` executable not found.', {
+        'Install `gcc` with your package manager.',
+        'Install `clang` with your package manager.',
+        'Check that your `$PATH` is set correctly.'
+      })
+  else
+    health_ok('`cc` executable found.')
+  end
+end
+
 -- TODO(vigoux): Maybe we should move each check to be perform in its own module
 function M.checkhealth()
   -- Installation dependency checks
   health_start('Installation')
-  install.checkhealth()
+  configs_health()
 
   local missing_parsers = {}
   -- Parser installation checks
-  for parser_name, repo in pairs(install.repositories) do
+  for parser_name in pairs(configs.repositories) do
     local installed = #api.nvim_get_runtime_file('parser/'..parser_name..'.so', false)
 
     -- Only print informations about installed parsers
@@ -42,7 +64,7 @@ function M.checkhealth()
 
     -- TODO(vigoux): The installation command should be changed so that its easier to find
     health_warn('Some parsers are not installed:\n' .. table.concat(missing_parsers, '\n'), {
-      "Install them using `:lua require'nvim-treesitter'.install_parser('language')`"})
+      "Install them using `:TSInstall language"})
   end
 end