Runtime selection of IONIC (#272)

* Split ionic code to a subdirectory; dyld libionicl; move the fntable to provider_gda_xxx.hpp
pass the pattr to ionic_setup_pd, include endian.hpp
Enable building IONIC conduit for runtime selection

* Uniform style for the fntable between ionic and the rest

* Move mlx5 gda conduit to a subdir; resolve conflict with backend_can_run
function

* Don't forget to init qp for ionic, move mlx5 specialized init qp code to
the mlx5 subdir

* Don't add cmakecaches...

Typo: GDA_BXNT

* Add gda-ionic to all_backends build scripts

* Apply suggestion from reviews

Co-authored-by: Omri Mor <omri50@gmail.com>
Co-authored-by: Edgar Gabriel <edgar.gabriel@amd.com>

* Remove duplicate definitiion of DLSYM macros

---------

Co-authored-by: Omri Mor <omri50@gmail.com>
Co-authored-by: Edgar Gabriel <edgar.gabriel@amd.com>

scripts/build_configs/all_backends

@@ -40,7 +40,7 @@ cmake \
     -DUSE_GDA=ON \
     -DGDA_MLX5=ON \
     -DGDA_BNXT=ON \
-    -DGDA_IONIC=OFF \
+    -DGDA_IONIC=ON \
     -DUSE_RO=ON \
     -DUSE_IPC=ON \
     -DUSE_THREADS=OFF \