fix repeated upscaler models + cmd flag for dat models

[light-and-ray]

Description

Alternative fix for repeated models if symlink is used #15035

I think it's better to not resolve every paths. It's not only about upscalers. this normalized_filepath touches SD, VAE, LORA etc models too. If someone wants to change symlink with not restarting the webui, the previous implementation wont allow it. So I think this way is better

• cmd flag for dat models

Checklist:

• I have read contributing wiki page
• I have performed a self-review of my own code
• My code follows the style guidelines
• My code passes tests