[WIP] Ensure LoRA files are only linked to the LoRA directory

[Rokurolize]

The LoRA files were also linked to the directory where the model files are located, so I added a condition to the check process. In addition, I thought I would lowercase it to match the other directories.

[Cyberes]

The official documentation says that Lora models should go in models/Lora https://github.com/AUTOMATIC1111/stable-diffusion-webui/wiki/Features#extra-networks

Did they change something?

[Rokurolize]

Since the only lower-case letters are for directories under model_storage_dir, the directory structure of the WebUI remains the same.
I saw that the VAE directory in the WebUI was uppercase and the VAE directory under model_storage_dir was lowercase, so it was a lighthearted idea to make lora lowercase as well.
However, I realized that some users might have already created a Lora directory and stored it under /storage, so it could cause confusion. Therefore, I will remove the lower case changes later.

EDIT: Done.

[Rokurolize]

Since Lora models can also be placed and used in subdirectories of the Lora directory, I noticed that Lora models placed in such a deep hierarchy are not excluded and are still linked to both the Lora directory and the SD model directory. So this fix is not sufficient. I will fix it later.

[pbuyle]

Lora are later properly linked from Path(model_storage_dir, 'Lora') to webui_lora_model_path. But the link_ckpts which run first also links them to webui_sd_model_path. As result, they appears in the checkpoints selection dropdown. This PR fix es the link_ckpts function so LoRAs are ignored when linking checkpoints (like vaes and hypernetworks are).

[xxBLUECATxx]

Lora are later properly linked from Path(model_storage_dir, 'Lora') to webui_lora_model_path. But the link_ckpts which run first also links them to webui_sd_model_path. As result, they appears in the checkpoints selection dropdown. This PR fix es the link_ckpts function so LoRAs are ignored when linking checkpoints (like vaes and hypernetworks are).

But no matter what, it will not affect the use of Lora right?