Show entity.update.resolve events in entity feed

[matthew-white]

Closes getodk/central#534.

What has been done to verify that this works as intended?

I viewed it locally and wrote new tests.

Why is this the best possible solution? Were any other approaches considered?

I tried to follow existing patterns.

Before submitting this PR, please make sure you have:

• run npm run test and npm run lint and confirmed all checks still pass OR confirm CircleCI build passes
• verified that any code or assets from external sources are properly credited in comments or that everything is internally sourced

[sadiqkhoja]

Looks good!