EOSIO.CDT To CDT

For this release all of the naming of namespaces and file paths will remain as eosio, so there is no need to migrate away from that with this release.

But there are a few differences.

1. The tool names have change prefix. I.e. tools like eosio-cpp are now cdt-cpp.
2. The CMake toolchain file has changed its name from EosioWasmToolchain.cmake to CDTWasmToolchain.cmake.
3. The library path for the CMake package has changed from /usr/local/lib/cmake/eosio.cdt to /usr/local/lib/cmake/cdt (or alternatively from /usr/lib/cmake/eosio.cdt to /usr/lib/cmake/cdt if installing from the Debian package). Additionally, the name to use with CMake find_package has similarly changed: use find_package(cdt) now instead of find_package(eosio.cdt).