[FEATURE] VCC CLI: Allow searching packages by repo ID

[LeafyLuigi]

I'm frustrated in being unable to search by repo ID when searching for what packages exist in a repo. I'd need to find the URL of each added repo within .../VRChatCreatorCompanion/Repos/$repo.json, opening up the file, finding the value for "url" and searching using that.

vpm list repo should be able to handle an existing added repo ID (such as com.vrchat.repos.official) and then searching by the URL held within (in the case of the aforementioned, the url is https://packages.vrchat.com/official).