Remove the Classy dependency for D10 compatibility

vmarchuk → made their first commit to this issue’s fork.

Opened MR with the fixes. Since we don't know in which version of commerce the payment_messages library will be available, we need to add it dynamically (check if it exists and then add it).

I added the old classes back so styles won't break on existing sites.

Merged!

Automatically closed - issue fixed for 2 weeks with no activity.