Allow coverage to be displayed using Flags or Components

[eliatcodecov]

We should allow the user to filter coverage for any particular file by any Flags or Components that they may be using. This can be accomplished with the /report endpoint and the /flags and /components endpoints.

This functionality, due to its complexity, should likely only be present when viewing a single file on a commit or branch (e.g., https://github.com/codecov/uploader/blob/main/src/index.ts) , but future work may attempt to show flag coverage on a Pull Request as well.

An example UI element is as follows, but note that if a more suitable element exists (such as a multiselect) it should be used:

This is likely the most complex feature to build into the integration, and should be prioritized after other items (excluding low priority items, which should go last).

[eliatcodecov]

completed as part of current beta release