Override branch name `master` with the correct release branch when installing

* Adding in a new go-agent to use for marketing pipelines. Contains necessary modules to make requirements in edx-mktg

* Setting up the go-agent with a name and resources so it will autoregister with these.

* Leaving php and drush is goagent so we can fall back. Making docs more clear

* Build go-agent-marketing based on tagged image of go-agent

* Attempting to fix build

* Trying latest

* Adding the acquia github key directly into the goagent (#4264)

* Adding the acquia github key directly into the goagent

* Moving the acquia key to the marketing agent

EDUCATOR-1664

This change makes Ansible run, but it has errors

Credentials role was revamped, build a new ame based on that ansible.

A demo site and configuration are now created for credentials sandboxes. This allows developers to provision a sandbox with no additional manual effort.

LEARNER-816

EDUCATOR-1470