pyosys: rewrite using pybind11

- Rewrite all Python features to use the pybind11 library instead of boost::python.
  Unlike boost::python, pybind11 is a header-only library that is just included by Pyosys code, saving a lot of compile time on wheels.
- Factor out as much "translation" code from the generator into proper C++ files
- Fix running the embedded interpreter not supporting "from pyosys import libyosys as ys" like wheels
- Move Python-related elements to `pyosys` directory at the root of the repo
- Slight shift in bridging semantics:
  - Containers are declared as "opaque types" and are passed by reference to Python - many methods have been implemented to make them feel right at home without the overhead/ambiguity of copying to Python and then copying back after mutation
  - Monitor/Pass use "trampoline" pattern to support virual methods overridable in Python: virtual methods no longer require `py_` prefix
- Create really short test set for pyosys that just exercises basic functionality

.github/workflows/wheels.yml

@@ -55,11 +55,6 @@ jobs:
           submodules: true
           persist-credentials: false
       - uses: actions/setup-python@v5
-      - name: Get Boost Source
-        shell: bash
-        run: |
-          mkdir -p boost
-          curl -L https://github.com/boostorg/boost/releases/download/boost-1.86.0/boost-1.86.0-b2-nodocs.tar.gz | tar --strip-components=1 -xzC boost
       - name: Get FFI
         shell: bash
         run: |
@@ -103,21 +98,16 @@ jobs:
           CIBW_BEFORE_ALL: bash ./.github/workflows/wheels/cibw_before_all.sh
           CIBW_ENVIRONMENT: >
             OPTFLAGS=-O3
-            CXXFLAGS=-I./boost/pfx/include
-            LINKFLAGS=-L./boost/pfx/lib
             PKG_CONFIG_PATH=./ffi/pfx/lib/pkgconfig
-            makeFlags='BOOST_PYTHON_LIB=./boost/pfx/lib/libboost_python*.a'
             PATH="$PWD/bison/src:$PATH"
           CIBW_ENVIRONMENT_MACOS: >
             OPTFLAGS=-O3
-            CXXFLAGS=-I./boost/pfx/include
-            LINKFLAGS=-L./boost/pfx/lib
             PKG_CONFIG_PATH=./ffi/pfx/lib/pkgconfig
             MACOSX_DEPLOYMENT_TARGET=11
-            makeFlags='BOOST_PYTHON_LIB=./boost/pfx/lib/libboost_python*.a CONFIG=clang'
+            makeFlags='CONFIG=clang'
             PATH="$PWD/bison/src:$PATH"
           CIBW_BEFORE_BUILD: bash ./.github/workflows/wheels/cibw_before_build.sh
-          CIBW_TEST_COMMAND: python3 {project}/tests/arch/ecp5/add_sub.py
+          CIBW_TEST_COMMAND: python3 {project}/tests/pyosys/run_tests.py python3
       - uses: actions/upload-artifact@v4
         with:
           name: python-wheels-${{ matrix.os.runner }}

.github/workflows/wheels/cibw_before_build.sh

@@ -11,24 +11,3 @@ if [ "$(uname)" != "Linux" ]; then
 fi
 python3 --version
 python3-config --includes
-
-# Build boost
-cd ./boost
-## Delete the artefacts from previous builds (if any)
-rm -rf ./pfx
-## Bootstrap bjam
-./bootstrap.sh --prefix=./pfx
-## Build Boost against current version of Python, only for
-## static linkage (Boost is statically linked because system boost packages
-## wildly vary in versions, including the libboost_python3 version)
-./b2\
-    -j$(getconf _NPROCESSORS_ONLN 2>/dev/null || sysctl -n hw.ncpu)\
-    --prefix=./pfx\
-    --with-filesystem\
-    --with-system\
-    --with-python\
-    cxxflags="$(python3-config --includes) -std=c++17 -fPIC"\
-    cflags="$(python3-config --includes) -fPIC"\
-    link=static\
-    variant=release\
-    install