v0.2.0: rename module to github.com/pgplex/pgparser and parser fixes

Breaking Changes:
- Rename module from github.com/bytebase/pgparser to github.com/pgplex/pgparser

Bug Fixes:
- Pass storage mode in SET STORAGE and set InitiallyValid for column CHECK
- Translate 8 missing grammar rule assignments
- Handle DISTINCT clause in SELECT statements

fix: remove accidental worktree submodules