Create CMake snippet for libdeepstream

[frobware]

[frobware]

It is customary to use:

FindFOO

in CMake files.

We need to create the equivalent for deepstream so that a client can add this to their CMakeLists.txt as:

FindLibary(deepstream)

Doing so allows them to get the right set of include and library directives (for the platform that is being built) without them having to understand how libdeepstream is built and whether or not it has any additional dependencies.

It is customary to also include this file when doing make install.