[Feature] support for other sources of Scoop app and main buckets

[xxthunder]

Description:

I love Scoop and want to support "offline" usage in my company. Therefore I tackled an already existing TODO:

Install/install.ps1

Line 680 in 656e17b

# TODO: Use a specific version of Scoop and the main bucket

[xxthunder]

Any review and improvement comments are welcome.

[xxthunder]

@rashil2000 @chawyehsu Hi, any feedback on this change from your side would be very welcome.

[xxthunder]

@chawyehsu Hi, any update on this? Not wanted? I thought it would be a good idea to contribute this change back to the repo. Using it for a while now at my company and it works pretty good. I would highly appreciate any feedback from you. 😄