[drizzle-kit] Add push flag for safe use in non-interactive CI

[carderne]

I know the docs suggest using drizzle-kit push in CI is a bad idea, but it works fine if you only do backward-compatible changes, and the push command is so close to supporting this use-case.

All it needs is an option to only to non-destructive stuff, which I've added here as a --safe flag.

I just put this up as a feeler covering the most basic use case of data loss. It should also handle things like making a column unique or notNull, by defaulting to try the change in a safe way (option 0), failing if it doesn't work.

Usage example

> drizzle-kit push --safe

[✓] Pulling schema from database...
 Warning  Found data-loss statements:
· You're about to delete foo column in bar table with 10 items

Safe mode is enabled - aborting

Todo

• handle unique/notNull etc constraints
• choose a better name for the flag than --safe? Could be --no-data-loss or --non-interactive...?
• add tests
• test it more
• update docs

Relevant issues

#3209