Merge Meltano and Custom taps/targets

A note from !237 (merged):

Its important to note that for now since it was a little complex to blend them I decided that if there was a meltano optimized definition and a custom tap/target definition then I will just take the meltano one. My thought is that later we can combine the two files into a comprehensive single file.

If its not solved by #203 (closed) already we should make sure that we find a way to merge the Singer plugins listed in discovery.yml with the Singer plugins in the hub when they exist in both places. Right now we are just taking the discovery.yml definition if they both exist.

Update 2022-05-27

From #240 (comment 962936968)

The proposed plan to bring the current hub up to speed so it can do the job for meltano 2.0 before the redesign is complete:

  • refresh the hub meltano files https://gitlab.com/meltano/hub/-/tree/main/\_data/meltano based on any recent discovery.yml updates
  • implement the new blended yaml schema (currently only implemented in the hub redesign repo https://gitlab.com/meltano/hub-v2/-/tree/develop/data/plugins) in the current hub
  • do a one time manual update to any extractors/loaders that have missing variants due to the challenge of being added only to the custom defintion and not to discovery.yml
  • make any necessary updates to the API to serve the new files
  • make any necessary front end changes to use the new file format

This issue will primarily be used for the updates.

Edited by Taylor A Murphy