Verify mongo repo and enterprise repo and in sync on scons compile

I personally do not do much work in the enterprise repo. I often try to compile without ensuring that my enterprise repo and mongo repo are in sync. I think we could automate it under certain conditions such as

1. if the enterprise repo is on the mongo branch
2. There are changes made to the branch (uncommitted or committed)

This could be automated with some flag `–doNotUpdateEnterprise` or something

This could also only be triggered by a flag `–updateEnterprise` or something

After discussion in standup we decided on:

This should be a check that should not update any repos 

This check should only run on developer workstations

This should make sure the base commit of the mongo repo and the base commit of the enterprise repo are in sync

This should instantly fail the build if they are not in sync with and output a message with the correct enterprise base commit to rebase on

There should be a flag to bypass this check

Most of the work for this ticket is already implemented in the `check_git_repos` function in the `validate_env.py` script