feat: fix bucket_id calculation, add tests for checking table format, parameters and columns nullability

Summary

These MR introduce several changes:

• BREAKING CHANGE: calculate_bucket_id function is fixed
• Test for checking table format is added (needed for checking columns nullable property)
• Tests for correct INSERT/SELECT are added (needed for checking correct columns definition)
  • is_nullable column metadata is added
• Test for correct parameters number added

Ensure that

• New code is covered by tests
• API is documented
• Changelog is up to date
• (if Lua API changed) Lua API version is bumped in luamod.rs
• (if necessary) A follow-up doc issue is created in picodata/docs and linked here