feat(webui): detect gpu automatically without manual choice

[vincenthou]

When I share this awesome project with many friends, they feel it is annoying to check the GPU type by themselves

[jllllll]

While I understand not wanting to type a single letter when first installing the webui, it is the simplest way to support multiple system configurations. Auto-detection may not work how you expect on every system. Regardless, there are more fundamental issues with your code that need to be addressed:

• You seem to only be accounting for Windows and Mac users. Linux users are being forced to go CPU-only.
• Macs have AMD GPUs that are, in fact, supported through Metal, which in turn is supported through the CPU-only option. Macs with AMD GPUs will no longer be able to install the webui. This will result in confusing and frustrating Mac owners.
• AMD GPU owners in general are being denied access to the webui even though they could previously still use it through the CPU-only option. This is why the option was given in the first place.

[oobabooga]

I think that it's harmless and easy to type a character