Replace Minitest with RSpec: bigbluebutton_api_controller specs (1)

Description

Reverse the logic for checksum check: Before, we had to disable the checksum check in (almost) every test. But, considering most of the tests are not testing the checksum specifically, the checksum check is now disabled by default for all the specs and has to be enabled when testing the checksum specifically.
In #create, a voiceBridge attribute is provided in every #create request to bypass the voiceBridge generator. This is because the stubbed request will never match the outside request as a voiceBridge generated and added to the uri by Scalelite.
Removed the redis_helper file as we will be using fakeredis and we don't need to configure a redis database for the test environment

The order of the parameters in a URL query string should not affect the functioning of the API request. For example, in #create, override_create_params adds the new params at the end of the uri, and default_create_params adds them at the beginning of the uri. Not following the order will return a different checksum value.