Painting mode properties don't have descriptions

### Tested versions

4.5 beta5

### System information

W10

### Issue description

TileSet editor shows descriptions for tile properties when in Select mode

However they don't show in Paint mode

The problem is that Paint mode does not use EditorInspector, so the custom descriptions can't be copied over directly. It does use EditorProperties though, so it should be possible to resolve. The Select mode descriptions were added in #85868

### Steps to reproduce

1. Create a TileSet
2. Add some atlas
3. In the Paint mode, select a property and hover its name

### Minimal reproduction project (MRP)

N/A

Compare how the TileSet editor displays property descriptions in Select mode versus Paint mode. Start by tracing the Paint mode's use of EditorProperties and contrast it with the Select mode's EditorInspector handling, using the listed reproduction steps. Done means tile property descriptions appear when hovering property names in Paint mode as they do in Select mode.

Written by the indexing model from the issue text.