Add branch / tag selection for template sources

[donkeyDau]

Description

Selection of branch or tag in the configuration section for templates.

Motivation and Context

Was not able to find any information about targeting a specific branch.

[derek]

Thank you for your contribution. I've just checked and your commit doesn't appear to be signed-off. That's something we need before your Pull Request can be merged. Please see our contributing guide.
Tip: if you only have one commit so far then run: git commit --amend --signoff and then git push --force.