Move PG_TEMP_FILE* macros to file_utils.h.

Move PG_TEMP_FILE* macros to file_utils.h.

Presently, frontend code that needs to use these macros must either
include storage/fd.h, which declares several frontend-unsafe
functions, or duplicate the macros.  This commit moves these macros
to common/file_utils.h, which is safe for both frontend and backend
code.  Consequently, we can also remove the duplicated macros in
pg_checksums and stop including storage/fd.h in pg_rewind.

Reviewed-by: Michael Paquier
Discussion: https://postgr.es/m/ZOP5qoUualu5xl2Z%40paquier.xyz