Support class static blocks

[Shraymonks]

Add support for static blocks in classes. Fixes https://github.com/tree-sitter/tree-sitter-javascript/issues/222

References: MDN TC39 spec

Checklist:

• [x] All tests pass in CI.
• [x] The script/parse-examples passes without issues.
• [x] There are sufficient tests for the new fix/feature.
• [x] Grammar rules have not been renamed unless absolutely necessary.
• [x] The conflicts section hasn't grown too much.
• [x] The parser size hasn't grown too much (check the value of STATE_COUNT in src/parser.c).

[aryx]

you can probably rebase on latest to fix the windows CI failure.

[Shraymonks]

you can probably rebase on latest to fix the windows CI failure.

Rebased!