General Cleanup

[mdemoret-nv]

This fixes the folllowing:

• Set SRF_USE_CONDA=ON as the default
• Removes MatX dependency
• Clean up all CMakeLists.txt
• Removing srf::make_pipeline() in favor of srf::pipeline::make_pipeline()
• Cleaned up comments from ./python
• Adding YAPF to the python CI checks
• Corrects #include "srf/... to the correct #include <srf/...>
• Re-enables architect and test to be checked by CI
• Adds a check for #pragma once to the cpp_tests.sh
• Combined common_sinks.cpp and common_sources.cpp into a single file since they have a single header.
• Cleans up all copyright headers
• Large cleanup of IWYU errors
• Deleting all checked files in Delete Unused Files from Repo #48
• Renaming include/srf/internal to include/srf/engine
• Removing xtl and xtensor
• Updating .clang-format includes to sort includes correctly

Closes #48

[mdemoret-nv]

@drobison00 and @ryanolson Can I get a re-review?

[mdemoret-nv]

@gpucibot merge