Organize embeddings in directories

[DevilaN]

Is your feature request related to a problem? Please describe.
I don't like the fact, that all embedding files are in one directory and can be used with all models.
Having a lot of embeddings leaves us with a mess in embeddings directory. It is not clear whenever which embedding can be used with which model (I know that you can use them with any model, but most of them are created for specific model and gives undesired / bad results with other ones).

Describe the solution you'd like
I would like to organize embeddings in directories.
embeddings

\_ 7460a6fa-vanilla_v1.4
|   \_ fileA.pt
|   \_ fileB.png
\_ 0b8c694b-Waifu_v1.2
|  \_ fileC.png
|  \_ fileD.pt
\_ file1.pt
\_ file2.png

Directory name starts with model hash, then rest of directory name is not obligatory (ignored, but helps users to find out which embeddings are for which model).
Embedding files placed in root of embeddings directory are always used among all models (like it is working right now).
Embedding files placed in directories starting with hash of model are used only with this very model.
Also links between directories should be handled as I might want to use same group of models with Waifu 1.2 and 1.3 or some merge between different models. So I will simply link 0a1b2c3d-MyFancyModel_v0.1.2 to 0b8c694b-Waifu_v1.2 so there is no need to duplicate files.

Describe alternatives you've considered
None

Additional context
None