Add Fuzz target

Recently, oss-fuzz added support for bmcweb, but did it by checking in
a number of code patches.  This commit should get similar coverage by
hooking into the HTTP connection class, and using the unit test
code to inject bytes directly into a stream.  This can be improved over
time, but this is a good start.

Change-Id: I20b5d536cff1588a8387f2770c022516e1cd62d0
Signed-off-by: Ed Tanous <etanous@nvidia.com>