Marketplace: Refactor marketplace catalog

Not sure if this is worth doing at the moment depends if this class is going to stick around or not.

Expand on D87621-code and D87613-code to refactor marketplace catalog into a singleton pattern and lazy load the network requests.

Context: p1663053733138519-slack-C4E0DVDB2

- [ ] Marketplace catalog wraps a singleton
- [ ] Move cached ~network~ db requests out of the constructor
- [ ] Split up the ~network~ db requested product data from the list of products
- [ ] Creating a marketplace catalog instance shouldn't hit the ~network~ db

Start by reviewing D87621-code and D87613-code, then locate the current marketplace catalog implementation. Confirm whether the class is still planned to remain before pursuing the refactor. Done means satisfying the checklist: singleton wrapping, no requests during construction, separated product data, and lazy request loading.

Written by the indexing model from the issue text.