Add some runtime asset importing/exporting benchmarks

[OverloadedOrama]

Adds benchmarks for runtime importing the Sponza scene as a gltf and fbx file, exporting it as gltf, importing 200 webp images and 50 ogg audio files, taken from Kenney's RPG Audio.

Basically these are runtime versions of benchmarks proposed in #36, so I'm not sure if this PR allows any of them to be ticked off, but the files introduced in this PR can later be used to tackle the startup asset importing benchmarks.

For images, I used load() instead of Image.load_from_file() because of warnings stating that using this method on images inside res:// doesn't work on export. If we don't care about this and Image.load_from_file() is preferred, let me know so I can change that.

Results on my PC

{
"benchmarks": [
{
"category": "Asset Import Export > Runtime",
"name": "Export Gltf",
"results": {
"time": 122.7
}
},
{
"category": "Asset Import Export > Runtime",
"name": "Import Fbx",
"results": {
"time": 838.7
}
},
{
"category": "Asset Import Export > Runtime",
"name": "Import Gltf",
"results": {
"time": 37.01
}
},
{
"category": "Asset Import Export > Runtime",
"name": "Import Ogg Audio",
"results": {
"time": 19
}
},
{
"category": "Asset Import Export > Runtime",
"name": "Import Webp Images",
"results": {
"time": 949.4
}
}
],
"engine": {
"version": "v4.3.beta2.official",
"version_hash": "b75f0485ba15951b87f1d9a2d8dd0fcd55e178e4"
},
"system": {
"cpu_architecture": "x86_64",
"cpu_count": 12,
"cpu_name": "AMD Ryzen 5 1600 Six-Core Processor",
"os": "Linux"
}
}

[Calinou]

Tested locally, it works as expected.

Thanks!