NEW Give feedback of password strength

[emteknetnz]

Issue #11413

This PR is part of a POC to give UX feedback of the new password

[GuySartorelli]

You might want to add a bit of a description about what you're actually doing here, because it's clearly more than just changing the default from "strong" to "medium"

[emteknetnz]

Updated description, this PR is just a POC

[christopherdarling]

Many users won't really understand what medium / strong passwords are and maybe what's missing to meet the medium strength. Is it possible to include in the notice some feedback of what is missing? or maybe if easier, what the medium strength criteria is?

[GuySartorelli]

The criteria is entropy based for the default password validator in CMS 6, so it's not a matter of meeting specific rules like "must have at least 15 characters total" or "must have at least one number" - and since we're using symfony's validation component for it they could change the specific implementation details at any time. Any specific details we give would be verbose and prone to becoming outdated.