feature: add plugins query

Summarize the changes

RFC: https://docs.google.com/document/d/1zfpo-oaprdQGvxXuJbnFMEhvM3Ug_8qFY9sftU2MIJs

PLUGIN RFC: https://docs.google.com/document/d/1QMFXWhrSJ9VLFNX-jayHCzG8jk01VwtOuTOzooBBsOA/edit#heading=h.ue9yhktcy3oc

Picodata issue: picodata#664 (closed)

Picodata mr: picodata!1163 (merged)

New queries:

• CREATE PLUGIN
• DROP PLUGIN
• ALTER PLUGIN ENABLE
• ALTER PLUGIN DISABLE
• ALTER PLUGIN MIGRATE TO
• ALTER PLUGIN ADD TIER
• ALTER PLUGIN REMOVE TIER
• ALTER PLUGIN SET (config key value)

Ensure that

• New code is covered by unit and integration tests.
• Related issues would be automatically closed with gitlab's closing pattern (Closes #1, #2).
• 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.

Next steps

• Cherry-pick to: none
• Update sbroad submodule in picodata/picodata. picodata!1163 (merged)
• (if EBNF grammar is changed) create a follow-up issue in picodata/docs - docs#349 (closed)