Add $PUSHOPT / $POPOPT directives for Delphi compatibility

Summary

Delphi 13 Florence has finally introduced $PUSHOPT/$POPOPT directives for saving and restoring the compiler state, which FPC has had for a long time as $PUSH/$POP. Perhaps it would be worth making them aliases, like it's already the case for $PACKENUM and $MINENUMSIZE, its Delphi counterpart.

Relevant 3rd party information

https://docwiki.embarcadero.com/RADStudio/Florence/en/What's_New#.7B.24PUSHOPT.7D_and_.7B.24POPOPT.7D_Directives
https://docwiki.embarcadero.com/RADStudio/Florence/en/Option_OPT_(Delphi)