Right now spo eventreceiver get is returning a list of objects with only 1 object in it. get commands should output a single object instead of a list of objects.

To do

1. Make sure the command outputs a single object instead of a list.
2. Throw an error when an event receiver with a specific name was not found.
3. Update spo eventreceiver remove command since it makes use of this command.
4. Update the v6 upgrade guidance.

Blocking PR

This issue is blocked until this PR has been completed:

• Fixes 'spo eventreceiver remove' command #4034