CONTRIB/IBMOCK: Inital add with EFA support

[tvegas1]

What

Add IB mocking (EFA support) capability.

Why ?

Need to run gtest without the need for EFA interface.

How ?

Implement loopback libibverbs/libefa. Keep build/code independent from UCX libraries.

Perftest/Info

vdi$ export LD_LIBRARY_PATH=$(pwd)/../efa_mock/build:$LD_LIBRARY_PATH
vdi$ UCX_TLS=srd ucx_perftest -t tag_bw -l
vdi$ UCX_TLS=ud ucx_perftest -t tag_bw -l
vdi$ ucx_info -d

Gtest:

vdi$ export LD_LIBRARY_PATH=$(pwd)/../hpc-poc/ibmock/build

vdi$ ./test/gtest/gtest --gtest_filter=\
*ud*ud_verbs/uct_p2p_err_test.invalid_am_short_*:*ud_verbs/test_uct_ib_addr.fill_ah_attr*:*ucp_sockaddr*
...
[----------] Global test environment tear-down
[==========] 2328 tests from 121 test suites ran. (812387 ms total)
[  PASSED  ] 2328 tests.

vdi$ valgrind --leak-check=full  ./test/gtest/gtest --gtest_filter=\
*ud*-ud_verbs/uct_p2p_err_test.invalid_am_short_*:*ud_verbs/test_uct_ib_addr.fill_ah_attr*:*ucp_sockaddr*:ud_verbs/test_uct_perf.envelope*