Single to multiple regions conversion wizard

[TokisanGames]

Builds off of #374. Converts single storage resource file to multiple storage files and facilitates setup.

TODO

• Fix wizard menu
• Add wizard button to inspector https://x.com/passivestar_/status/1795886728646975820 if storage_dir is empty
• Update conversion wizard in GDScript
• Port wizard to C++
• Rename Terrain3DStorage to Terrain3DData
• Strip Terrain3DStorage down to convertable resource
• Convert demo
• Update docs

[Xtarsia]

[Xtarsia]

Instant crash with no logs:
open the artifact project, open node3d.tsn, add 1 region, change mesh size .

Posibly related: attempting to change mesh size when a very large number of regions are present causes serious lag, and even editor freezing until the mesh size change is complete.

Also: changing LOD and vertex spacing has the same effect as above.

[Xtarsia]

attempting to add regions by clicking outside the area, and then saving:

[TokisanGames]

The Directory setup wizard now works to upgrade an old version. Here are our alerts to begin our upgrade process. I don't think it can be any simpler than this when the user loads an old scene, and an inspector button is redundant.

• This pops up whenever a scene w/ a 0.9.2 storage loads.
• Console warning saying Use Terrain3D Tools / Directory Setup to upgrade
• Scene tree Terrain3D node yellow icon says the same, any time Data Directory is empty.
• Release notes saying the same

The popup is automatic and the old storage file is auto popuplated. All the user needs to do is specify a new directory, click ok. On save, it will write to disk.