add support for regenerating ids

[eth0net]

Description

This adds support for regenerating the id for a category, entity, or property. It also adds the ability to regenerate ids for all pandora items at once, to aid with migration from sequential ids to nanoids.

Addressed issues

• none

Screenshots

[eth0net]

One flaw right now: the list won't automatically update tooltips with the new IDs. They do update after a save and reload of items using the Pandora toolbar.

[eth0net]

One flaw right now: the list won't automatically update tooltips with the new IDs. They do update after a save and reload of items using the Pandora toolbar.

Fixed using _populate_data(), though this does cause the selected entry to be de-selected, which seems unnecessary.

[eth0net]

There were some whitespace changes done by Godot, so worth hiding whitespace when reviewing :)

[bitbrain]

A few things we may want to add:

• unit tests
• some basic docs of what the purpose of this functionality is (e.g. use cases, examples)

[bitbrain]

Thank you! Great PR.