feat(tests)!: new infrastructure based on makefile

Problem: Not easy to run all checks and tests locally. Redundant CI
workflows.

Solution: Separate CI into two workflows:
 * lint: Lua files (stylua, luals), query files (valid captures,
   predicates, directives using tsqueryls), docs
   (SUPPORTED_LANGUAGES.md) -- does not need parser installation
 * tests: parsers (ABI compatibility), query files (tsqueryls on
   Linux/macOS; nvim on Windows), highlight and indent tests (separated
   for better readability) -- needs parser installation (but only once)

Switch to https://github.com/nvim-treesitter/highlight-assertions fork
with ABI 15 support.

Run all tests (on Linux and macOS) through `make` (`formatlua`,
`checklua`, `lintquery`, `formatquery`, `checkquery`, `docs`, `tests`),
which downloads and caches all necessary dependencies.

Remove `update-readme` workflow (replaced by lint job on PRs).

tests/query/injection_spec.lua

@@ -6,24 +6,13 @@ local function check_assertions(file)
   vim.fn.bufload(file)
   local ft = vim.bo[buf].filetype
   local lang = vim.treesitter.language.get_lang(ft) or ft
-  assert.same(
-    1,
-    vim.fn.executable('highlight-assertions'),
-    '"highlight-assertions" not executable!'
-      .. ' Get it via "cargo install --git https://github.com/theHamsta/highlight-assertions"'
-  )
-  local assertions = vim.fn.json_decode(
-    vim.fn.system(
-      "highlight-assertions -p '"
-        .. config.get_install_dir('parser')
-        .. '/'
-        .. lang
-        .. ".so'"
-        .. " -s '"
-        .. file
-        .. "'"
-    )
-  )
+  local assertions = vim.fn.json_decode(vim.fn.system({
+    os.getenv('HLASSERT'),
+    '-p',
+    config.get_install_dir('parser') .. '/' .. lang .. '.so',
+    '-s',
+    file,
+  }))
   local parser = ts.get_parser(buf, lang)
 
   local top_level_root = parser:parse(true)[1]:root()