This PR adds a feature naming pattern description to the project form.
It's rendered as a multi-line input field. The description is also
stored in the db.
This adapts most of @andreas-unleash's PR #4599 with some minor changes
(using description instead of prompt). Actually displaying this data to
the users will come in a later PR.

Adds a first iteration of feature flag naming patterns. Currently behind a flag.
Signed-off-by: andreas-unleash <andreas@getunleash.ai>
Co-authored-by: Thomas Heartman <thomas@getunleash.io>
Co-authored-by: andreas-unleash <andreas@getunleash.ai>
Co-authored-by: Thomas Heartman <thomas@getunleash.ai>