BB2-5215 Add new secrets scanning setup

[annamontare-nava]

JIRA Ticket:
BB2-5215

What Does This PR Do?

Adds new secrets scanning setup to this repo.

What Should Reviewers Watch For?

If you're reviewing this PR, please check for these things in particular:

• Anything change that shouldn't?

Validation

• Add a fake secret to a file a try to commit, verify that betterleaks catches it.
• See that the GitHub Action passes
• See that betterleaks dir . -v finds no secrets.

What Security Implications Does This PR Have?

Please indicate if this PR does any of the following:

• Adds any new software dependencies
• Modifies any security controls
• Adds new transmission or storage of data
• Any other changes that could possibly affect security?

• Yes, one or more of the above security implications apply. This PR must not be merged without the ISSO or team security engineer's approval.

[JamesDemeryNava]

Looks good! No leaks and action is passing.