test(hashing/merkle_root): write test for empty vector and odd leaf count
test(hashing/merkle_root): write test for empty vector and odd leaf count

Signed-off-by: Johns Beharry <cda598379ee814427ba60a28a3d17fee64521a74@peakshift.com>

sigp/lighthouse,sigp/lighthouse,sigp/lighthouse,sigp/lighthouse