Description of change

Some databases transforms date functions to their aliases when the function used in column default, e.g. CURRENT_TIMESTAMP stored as now() in PostgreSQL. This PR adds mapping for these functions to fix synchronization problems.

• PostgreSQL:
  • CURRENT_TIMESTAMP -> now()
  • CURRENT_TIMESTAMP(precision) -> ('now'::text)::timestamp(precision) with time zone
  • CURRENT_DATE -> ('now'::text)::date
  • CURRENT_TIME -> ('now'::text)::time with time zone
  • CURRENT_TIME(precision) -> ('now'::text)::time(precision) with time zone
  • LOCALTIME -> ('now'::text)::time without time zone
  • LOCALTIME(precision) -> ('now'::text)::time(precision) without time zone
  • LOCALTIMESTAMP -> ('now'::text)::timestamp without time zone
  • LOCALTIMESTAMP(precision) -> ('now'::text)::timestamp(precision) without time zone
• SQLServer:
  • CURRENT_TIMESTAMP -> getdate()
• CockroachDB
  • CURRENT_TIMESTAMP -> current_timestamp()
  • CURRENT_DATE -> current_date()
• MySQL:
  • CURRENT_TIMESTAMP() -> CURRENT_TIMESTAMP
• MariaDB:
  • CURRENT_TIMESTAMP -> CURRENT_TIMESTAMP()

fixed issues:

Fixes #2136
Fixes #2718
Fixes #2737
Fixes #3561
Fixes #3991
Fixes #6412
Fixes #6579
Fixes #7381

covered pull-requests:

Closes #7229

Pull-Request Checklist

• Code is up-to-date with the master branch
• npm run test passes with this change
• npm run lint passes with this change
• This pull request links relevant issues as Fixes #0000
• There are new or updated unit tests validating the change
• N/A Documentation has been updated to reflect this change
• The new commits follow conventions explained in CONTRIBUTING.md