feat: add first version of WHITESPACEs grammar fix

Summarize the changes

• feat: add first version of WHITESPACEs grammar fix

Closes #640 (closed)

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.