ci: add linting and formatting automation to tree-sitter grammar

[ttytm]

The PR ensures better code consistency and standards.

• For linting it adds eslint (commonly used for linting in js projects and by official tree-sitter grammars, e.g., rust, go, bash).
• It adds a prettier config file.
• Adds steps to run linting and verify formatting to the tree-sitter workflow.

The PR makes uses of the above to fix lint warnings and to format the code.
To verify those fixes and the formatting didn't change the grammar, the current parser.c can be re-generated and confirmed that it didn't change.