Remove `skip_false=True` and `--no-skip-false` in `sqlite-utils` 4.0

[simonw]

Following:

• 527

The only reason I didn't remove fix this mis-feature entirely is that it represents a backwards incompatible change. I'll make that change in 4.0.

[simonw]

Relevant commits (will mostly revert these):

• https://github.com/simonw/sqlite-utils/commit/455c35b512895c19bf922c2b804d750d27cb8dbd
• https://github.com/simonw/sqlite-utils/commit/e0ec4c345129996011951e400388fd74865f65a2