v3 without conan

[rturrado]

CMake

Updated C++ version to C++23. Updated GitHub Actions to build in gcc/clang/msvc x Linux/MacOS/Windows x Debug/Release. Updated dependency management to be done through FetchContent instead of git submodules.

• CMake minimum required version is now 3.25, due to FetchContent_Declare(... SYSTEM).
• lemon dependency is now fetched through a fork, which fixes C++17 & 20 compilation, and some CMake and C++ warnings.

Reorganized tests, examples, and resources.

Reorganized tests.

• All tests are now under the test folder.
• All tests are googletest. doctest dependency has been removed.
• All tests are discovered. CMake code for adding tests has been removed.
• Python tests have been updated to comply to most of PEP 8 (code style guide).

Reorganized resources.

• All resources are now under the res folder.
• Some file names were changed.

Reorganized examples.

• All example codes are now under example folders within test.
• All example resources are now under example folders within res.

The structure of the test folder is:

  |- ql
  |  \- com, ir, pass, utils...
  \- v1x
     |- cpp
     |  \- example
     \- python
        |- example
        \- visualizer

The structure of the res/v1x folder is:

  |- cq
  |  |- example
  |  \- golden
  |- json
  |  \- visualizer
  \- qasm
     \- golden

v1x stands for cQasm v1.x. There may be folders such as v3x in the future.

File changes

• deps: removed.
• docs:
  • Changed from openql import openql as ql to import openql as ql.
  • Changed nqubits to num_qubits.
• include/ql, source/ql:
  • Fixed warnings and compilation errors.
  • Update references to resources to point to the new location in res.
• python/ql.i: minor aesthetic change: split a very whole string into different lines.
• .gitmodules: removed.
• CMakeLists.txt: C++23, FetchContent, ql target_compile_options.
• pytest.ini: updated testpaths to point to test/v1x/python.

[pablolh]

few comments I think this can be merged quickly!