XACC - Enfield Placement plugin

This branch implements an XACC placement plugin (IRTransformation) based on the Enfield library.

Build Instructions:

• Build the Dockerfile container. The Dockerfile will install XACC and other required libraries.

• Perform a standard build, i.e.

mkdir build && cd build
cmake ..
make install

• Run the unit test to veify the plugin if neeed:

ctest