Breestryker/restructure code

[Breanna-Stryker]

Description

Rename files and file contents to match new naming schemes. Modify readme's and add brief readmes to the new core and module folders.

Issue reference

The issue this PR will close: #561

Checklist

Please make sure you've completed the relevant tasks for this PR out of the following list:

• All acceptance criteria in the backlog item are met
• The documentation is updated to cover any new or changed features
• Manual tests have passed
• Relevant issues are linked to this PR

[lisamurphy-msft]

Testing to see if this deploys, using these parameters:
$ az deployment sub create --name "testing699" --location eastus --template-file bicep/mlz.bicep --parameters resourcePrefix=test deploySentinel=true deployDefender=true

[lisamurphy-msft]

Deployment completed successfully with all expected resources:

[lisamurphy-msft]

This is very well done and a significant amount of effort!!!
Testing also shows that the refactoring didn't break any of the deployment logic.
Approving.