AST-933 Add sphinx documentation

This builds sphinx documentation for a subset of C++ classes and python classes. The python documentation is not as complete as the C++ documentation, there will be a follow-up MR to fix that.

doc/CMakeLists.txt

-find_package(Doxygen)
-find_package(Sphinx)
-
-if(NOT (SPHINX_FOUND AND DOXYGEN_FOUND))
-  set(missing_packages "Doxygen and Sphinx")
-  if(SPHINX_FOUND)
-    set(missing_packages "Doxygen")
-  endif()
-  if(DOXYGEN_FOUND)
-    set(missing_packages "Sphinx")
-  endif()
-  add_custom_target(
-    doc
-    COMMAND
-      echo -e
-      "\\nTo make the documentation please install ${missing_packages}, rerun cmake and then run make doc\\n"
-    COMMAND exit 1
-    VERBATIM)
-else()
-  set(RADLER_SO_PATH ${CMAKE_BINARY_DIR}/python)
-
-  set(DOXYGEN_OUTPUT_DIR "${CMAKE_CURRENT_BINARY_DIR}/doxygen")
-  file(MAKE_DIRECTORY ${DOXYGEN_OUTPUT_DIR})
-
-  set(DOXYFILE_IN ${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile.in)
-  set(DOXYFILE_OUT ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile)
-
-  # Replace variables inside @@ with the current values
-  configure_file(${DOXYFILE_IN} ${DOXYFILE_OUT} @ONLY)
-
-  # This will be the main output of our command
-  set(DOXYGEN_INDEX_FILE "${DOXYGEN_OUTPUT_DIR}/xml/index.xml")
-
-  add_custom_command(
-    OUTPUT ${DOXYGEN_INDEX_FILE}
-    COMMAND ${DOXYGEN_EXECUTABLE} ${DOXYFILE_OUT}
-    WORKING_DIRECTORY ${DOXYGEN_OUTPUT_DIR}
-    MAIN_DEPENDENCY Doxyfile
-    COMMENT "Generating doxygen documentation")
-
-  set(SPHINX_SOURCE ${CMAKE_CURRENT_SOURCE_DIR})
-  set(SPHINX_BUILD ${CMAKE_CURRENT_BINARY_DIR}/html)
-
-  add_custom_target(
-    doc
-    ${CMAKE_COMMAND}
-    -E
-    env
-    RADLER_SO_PATH=${RADLER_SO_PATH}
-    ${SPHINX_EXECUTABLE}
-    -b
-    html
-    ${SPHINX_SOURCE}
-    ${SPHINX_BUILD}
-    # Tell Breathe where to find the Doxygen output
-    -Dbreathe_projects.Radler=${DOXYGEN_OUTPUT_DIR}/xml
-    WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
-    COMMENT "Generating documentation with Sphinx"
-    DEPENDS ${DOXYGEN_INDEX_FILE} pyradler)
-
-endif()
+find_package(Doxygen REQUIRED)
+find_package(Sphinx REQUIRED)
+
+set(RADLER_SO_PATH ${CMAKE_BINARY_DIR}/python)
+
+set(DOXYGEN_OUTPUT_DIR "${CMAKE_CURRENT_BINARY_DIR}/doxygen")
+file(MAKE_DIRECTORY ${DOXYGEN_OUTPUT_DIR})
+
+set(DOXYFILE_IN ${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile.in)
+set(DOXYFILE_OUT ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile)
+
+# Replace variables inside @@ with the current values
+configure_file(${DOXYFILE_IN} ${DOXYFILE_OUT} @ONLY)
+
+# This will be the main output of our command
+set(DOXYGEN_INDEX_FILE "${DOXYGEN_OUTPUT_DIR}/xml/index.xml")
+
+add_custom_command(
+  OUTPUT ${DOXYGEN_INDEX_FILE}
+  COMMAND ${DOXYGEN_EXECUTABLE} ${DOXYFILE_OUT}
+  WORKING_DIRECTORY ${DOXYGEN_OUTPUT_DIR}
+  MAIN_DEPENDENCY Doxyfile
+  COMMENT "Generating doxygen documentation")
+
+set(SPHINX_SOURCE ${CMAKE_CURRENT_SOURCE_DIR})
+set(SPHINX_BUILD ${CMAKE_CURRENT_BINARY_DIR}/html)
+
+add_custom_target(
+  doc
+  ${CMAKE_COMMAND}
+  -E
+  env
+  RADLER_SO_PATH=${RADLER_SO_PATH}
+  ${SPHINX_EXECUTABLE}
+  -b
+  html
+  ${SPHINX_SOURCE}
+  ${SPHINX_BUILD}
+  # Tell Breathe where to find the Doxygen output
+  -Dbreathe_projects.Radler=${DOXYGEN_OUTPUT_DIR}/xml
+  WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+  COMMENT "Generating documentation with Sphinx"
+  DEPENDS ${DOXYGEN_INDEX_FILE} pyradler)