cannot read data while 3dtiles tileset.json tile content uri has operator + like string Tile_+000_+000

### What happened?

Example:
http://127.0.0.1/path/to/data/Tile_+000_+000/tileset.json
when request content, + should be encoded as %2B
expect encoded url is http://127.0.0.1/path/to/data/Tile_%2B000_%2B000/tileset.json

### Reproduction steps

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### Sandcastle example

_No response_

### Environment

Browser:
CesiumJS Version:
Operating System:

No source file, test, or entry point is named. Start by tracing how CesiumJS requests 3D Tiles content URIs from tileset.json, then verify that plus signs in path segments are percent-encoded and add a regression test covering Tile_+000_+000.

Written by the indexing model from the issue text.