Add support for \exp \log \ln \det etc. in op.legacy

[Firestar-Reimu]

These are all operators supported by physics also Re Im

Especially the widely used \exp \log \ln \det

Thanks!

[Firestar-Reimu]

Maybe add some lines in https://github.com/AlphaZTX/physics2/blob/main/physics2-code.src.operator.dtx ?

[AlphaZTX]

@Firestar-Reimu 我前几天在贵校被电动车撞了，先养好伤再说。你可以自己修改文件，实在着急可以pr，不过，针对这个需求，我暂时不建议你pr。

[LHRG]

And there is \erf meaning Gauss error functions without \erfc meaning complementary error function. However, they often appear together in documents/books.
Could you please add \erfc in this beautiful package?