Consolidate azure-security, azure-security-hardening, and azure-nodejs-production

[tmeschter]

We're working to consolidate existing, fine-grained skills into bigger skills that take overall workflows into account.

The azure-security, azure-security-hardening, and azure-nodejs-production all deal with best practices and recommended approaches for Azure development; as such it makes sense to consolidate them all into the azure-prepare skill rather than keeping them separate.

[kvenkatrajan]

#794