refactor: refactor github-status service and PR data

[mcdurdin]

The github-status.ts service has grown unwieldy and needs to be broken up into separate components. Some of the data overlaps but not precisely. We should have one service to return all PR data and we already have a service returning issues from the main repo. Probably should generalized both to return data from the relevant repos and restructure the front-end to query this data.

Similar probably for github-contributions.ts