feat: totara compatibility

[matthewhilton]

Changes

• Adds some defined checks around constants that changed in 4.1 / 4.5 that Totara doesn't have.

Notes

• These changes are small enough that they should just be in the stable-catalyst branch, as opposed to making a whole new totara specific branch

[rhell4]

Looks good to me, I agree that these are so minor it's not worth creating another branch. It would be nice to get unit tests passing but I see they've always been failing and that might be a bigger task on its own.