feat(install)!: generate from json instead of requiring node

Problem: Many parsers require node/npm to evaluate the `grammar.js`
before being able to generate a parser from it.

Solution: Generate from `grammar.json` instead, which is fully resolved.
Drops `node` and `npm` as (optional) requirements for nvim-treesitter.

Note that this requires parsers to commit the generated json iff the
grammar requires evaluation (which is currently the case for all tracked
languages).

scripts/install-parsers.lua

@@ -1,14 +1,28 @@
 #!/usr/bin/env -S nvim -l
 
+local generate = false
+local parsers = {}
+for i = 1, #_G.arg do
+  if _G.arg[i] == '--generate' then
+    generate = true
+  else
+    parsers[#parsers + 1] = _G.arg[i]
+  end
+end
+
 vim.opt.runtimepath:append('.')
 
 -- needed on CI
 vim.fn.mkdir(vim.fn.stdpath('cache'), 'p')
 
 local done = false
-require('nvim-treesitter.install').install('all', {}, function()
-  done = true
-end)
+require('nvim-treesitter.install').install(
+  #parsers > 0 and parsers or 'all',
+  { force = true, generate = generate },
+  function()
+    done = true
+  end
+)
 
 vim.wait(6000000, function()
   return done