Move getEntityTableData logic into the backend

[krishnaglick]

The frontend has a method called getEntityTableData. It takes a set of sources or destinations, connections, and a source or destination definitions (which are a combined list of source or destination definitions along with their respective latest calls and data).
That's 4 API calls all to combine their data for frontend usage, as well as a lot of iteration. Moving all this logic into the backend lets us get that information in a single API call, and the data processing will be better places.

This should replace the sources/list or destinations/list calls for the sources list or destinations list pages.

[gosusnp]

Check feasibility and improvement on the backend beforehand to make sure we are tackling the right problem

[krishnaglick]

Upon further investigation it looks like we can remove the list_by_workspace and list_latest calls from this logic completely. It's not worth the lift to move the code into the backend and with the other improvements made to the connections list endpoint I think things are in a good state with the removal of those calls.