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).

.github/workflows/test-generate.yml

@@ -1,4 +1,4 @@
-name: Generate from grammar
+name: Tests
 
 on:
   pull_request:
@@ -8,12 +8,12 @@ on:
   workflow_dispatch:
 
 concurrency:
-  group: ${{ github.workflow }}-${{ github.ref }}
+  group: ${{ github.workflow }}-generate-${{ github.ref }}
   cancel-in-progress: ${{ github.event_name == 'pull_request' }}
 
 jobs:
   check_compilation:
-    name: Build
+    name: Generate
     if: contains(github.event.pull_request.labels.*.name, 'ci:generate') || github.event_name == 'workflow_dispatch'
     uses: ./.github/workflows/test-core.yml
     with: