Add regsync make target command

[rohitsakala]

JIRA Issue - https://jira.suse.com/browse/SURE-5868

Security Team Review Issue - https://github.com/rancher/security-team/issues/227

Implemented Solution 3 here - https://confluence.suse.com/display/EN/Rancher+Prime+Image+Publishing+for+OOB+Chart+Releases

TLDR

• This PR creates a make target when run against rancher/charts repository like make patch, will create a regsync config yaml for the EIO team to consume.
• This updated file will be committed along the OOB release PR.
• The EIO team will regularly check for this file and sync to its Prime registry.

[prachidamle]

Can we add in the description and the link to github issue that this PR is aiming to fix/improve?

[rohitsakala]

Can we add in the description and the link to github issue that this PR is aiming to fix/improve?

Done