⭐ Allow users to rename Flow namespace & id

[tchiotludo]

Since there is a lot of "foreign keys" on flow namespace + flow id, we need to implement a special method to move a flow and change the name.

The ui must be like on github with its "danger zone" (it will break all app using the flow).
The move method must changed the flow namespace & id, since the operation can be very long, it must be async.

Also, when a user want to change the namespace it encounters multiple “Page not found” before understanding that it wasn’t possible. We should at least improve the error message.

[anna-geller]

most of Page not found have been addressed - e.g. when the flow is deleted, going from the Execution of the deleted flow to the flow page, the Flow page is now displayed (no longer 404) but with a message that the flow is deleted and an option to restore it

also, given that the VS Code Editor allows opening multiple flows side by side, it seems like this is no longer a problem

@tchiotludo, if you feel we need to work on this, please reopen. For now, I think this is no longer an issue

[tchiotludo]

I think it's a nice feature to be able to rename a flow without losing their execution history IMO