Refactored `ColumnOption::Unique` to reuse `UniqueConstraint` and `PrimaryKeyConstraint`#2064

LucaCappelletti94 wants to merge 2 commits intoapache:mainapache/datafusion-sqlparser-rs:mainfrom

LucaCappelletti94:unique-unique-constraintLucaCappelletti94/sqlparser-rs:unique-unique-constraintCopy head branch name to clipboard