Drop procedure with sql api

Summarize the changes

• fix: trim trailing spaces in query.pest

• refactor: align grammar rules in doc

• feat: implement SQL support for drop procedure

Closes #563 (closed)

Ensure that

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

Next steps

• Update sbroad submodule in picodata/picodata.
• (if EBNF grammar is changed) create a follow-up issue in picodata/docs.