Improved control over tileset LOD selection

Over the years we've received various requests for more granular control over tileset selection. This issue is meant to track them all in one place.

### Generalized Selection

e.g., by bounding volume, or any other means besides a camera frustum

- #266
- #1237
- #1143
- https://github.com/CesiumGS/cesium-unreal/issues/1826

### Fixed LOD selection

i.e., fixing the level of detail that is chosen, or specifying a min/max

- https://github.com/CesiumGS/cesium-unreal/issues/1811
- https://github.com/CesiumGS/cesium-native/issues/616

### Higher flexibility with screen space error

- https://github.com/CesiumGS/cesium-unreal/issues/323
- #1399

No source files, tests, or entry points are named. Start by reviewing the linked issues under Generalized Selection, Fixed LOD selection, and Higher flexibility with screen space error to determine whether they share an implementation path. Done would require a defined, unified scope for tileset LOD selection controls.

Written by the indexing model from the issue text.