RFC: Rename `fastrace::full_name!()` to `fastrace::func_path!()`

[andylokandy]

fastrace has three macros for conveniently acquiring the current span name: func_name, full_path, and file_location. Among these three, full_path seems ambiguous. Other motivation is anyhow, who also provides two macros func_name and func_path.

Do you think this change is a good idea? @zhongzc @breezewish @Xuanwo @tisonkun @MrCroxx

[Xuanwo]

+1.

I think it's a good idea to rename it to func_name.

Maybe we also deprecate full_path first to make users easier to migrate?