Rescue Master Branch Commit ENH Prefer ::class syntax over class strings

[GuySartorelli]

Rescues and extends 43be1a0

There's no change to API here so it makes sense to target 1 so both major lines can benefit.

Parent issue

• Rescue master branch commits silverstripe-framework#10350

[emteknetnz]

This looks quite different from the rescued commit?

[GuySartorelli]

This PR rescues "and expands upon" the original PR.
I cherry-picked in the commit from the original PR and then looked for instances of what the original commit was doing which had been either missed or added since the original commit was created. The PR would be incomplete if these additional items were left unchanged, since the purpose is to update the old hardcoded string syntax.