refactor: make DEFAULT_VTABLE_MAX_ROWS and DEFAULT_VDBE_MAX_STEPS public

Summarize the changes

• refactor: make DEFAULT_VTABLE_MAX_ROWS and DEFAULT_VDBE_MAX_STEPS public

Ensure that

• [ ] New code is covered by unit and integration tests.
• [ ] Related issues would be automatically closed with gitlab's closing pattern (Closes #issue_number).
• [ ] Public modules are documented (check the rendered version with cargo doc --open).
• [ ] (if PEST grammar has changed) EBNF grammar reflects these changes (check the result with railroad diagram generator.

Next steps

• Cherry-pick to: none
• Update sbroad submodule in picodata/picodata.
• (if EBNF grammar has changed) create a follow-up issue in picodata/docs.