Refactor: surface useful show_ macros so they can be shared between
the client and server trace code.

Additional clean up:
- Housekeeping: ensure the correct #include files are pulled in
  and add proper TRACE_DEFINE_ENUM where they are missing
- Use a consistent naming scheme for the helpers
- Store values to be displayed symbolically as unsigned long, as
  that is the type that the __print_yada() functions take
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>