[FEATURE REQUEST] Custom mirror sources for pip and npm repositories

### Please confirm these before moving forward

- [X] I have searched for my feature proposal and not found a work-in-progress/duplicate/resolved/discarded issue.
- [X] This proposal is a completely new feature. If you want to suggest an improvement or an enhancement, please use [this template](https://github.com/marticliment/WingetUI/issues/new?assignees=marticliment&labels=enhancement&projects=&template=enhancement-improvement.yml&title=%5BENHANCEMENT%5D+%28Enter+your+description+here%29)

### Describe the new feature

Users can switch mirror sources for pip and npm repositories

### Describe how this new feature could help users.

Provide faster download speed and better experience for users in some countries or regions that use the official warehouse to download slowly