Expose statement list

[dvmarcilio]

Exposing statement_list productions so we can match child nodes of a block in a single capture without using quantifiers.

In Polyglot Piranha, we have the remove_unnecessary_nested_block which needs to match the contents of a block in a single multi-line capture.
This is made possible by capturing (statement_list) @nested.statements in the query below.
Polyglot Piranha then replaces @nested.block with @nested.statements.

(
    (block
        (statement_list
            (((_) "\\n"?)* @pre)
            ((block
                (statement_list) @nested.statements
            ) @nested.block)
            (((_) "\\n"?)* @post)
        ) @outer.stmt_list
    ) @outer.block
)

Checklist:

• All tests pass in CI.
• There are sufficient tests for the new fix/feature.
• Grammar rules have not been renamed unless absolutely necessary.
• The conflicts section hasn't grown too much.
• The parser size hasn't grown too much (check the value of STATE_COUNT in src/parser.c).