Perfomance metrics and research about freeing used memory

[leanmendoza]

No description provided.

[kuruk-mm]

Almost all the memory consumption was due to the Texture Sizes. We had 4k textures with more than 40mb in the VRAM, without any sense.

I did some tests with the following steps

1. Open Godot
2. Go to Genesis City
3. Wait to load everything

And the results were:

Without any resize:

Resizing to 256x256 all the textures from fetch_texture

Resizing to 256x256 all the textures from fetch_texture and all textures in GLTFs

With this result. We implemented a Texture Quality Setting, to have multiple quality of texture with the following table

QUALITY	MAX SIZE
LOW	256x256
MEDIUM	512x512
HIGH	1024x1024
SOURCE	INFxINF

To free memory, we added a reference counter to all the resources, and when they have not been accessed for the last 30 seconds, and the reference count is just retained by the cache, we release them.

All that work is in the following PR: #414