[Feature] Implement adding Custom Models via URL

[Algorithm5838]

Is your feature request related to a problem? Please describe.
The feature request isn't linked to a specific problem but aims to enhance user convenience and URL sharing.
Use case scenario: adding 'allowed' custom models when using a URL and API for one-api.

Describe the solution you'd like
To add custom models using URL, similar to openaiUrl and openaiApiKey.

Describe alternatives you've considered
The alternative considered is manual input, which is less efficient.

Additional context
None.