Hub Bot - Write target-meltanohub

[pnadolny13]

Related to https://github.com/meltano/hub/issues/699

Build a target that can take records from snowflake https://github.com/meltano/squared/issues/362 to make changes to the hub, commit them, push to github, and open a PR.

• the target will clone the hub, then for each record:
  • create new branch
  • add the new plugin variant
  • check if the maintainer exists or add it
  • commit changes
  • push to github
  • open PR (maybe draft PRs)
• the target would use a PR naming convention so it can query for open PRs and not open duplicates. Something like [MeltanoHub Bot] Add Plugin MeltanoLabs/tap-github
• for the case where a reviewer decides that the plugin isnt ready to be listed on the hub, maybe its still in development, we close the PR after review. The target wont open a duplicate but it can have logic to create a new PR if its been some amount of time since the last one, 1-3 months later maybe? Then we can re-review and evaluate it again. Something like [MeltanoHub Bot] Add Plugin MeltanoLabs/tap-github (Attempt 2)
• Explore using https://github.com/datafold/data-diff for checking changes