Review and Document new Qt 6.2 CMake API

Discussion and notes:

https://git.qt.io/alcroito/qt6-cmake-api-review/-/blob/master/api_review_qt_6_2.md

Gerrit changes:

https://codereview.qt-project.org/q/topic:%22cmake_api_review_6_2%22+(status:open%20OR%20status:merged)

New public API in Qt6CoreMacros.cmake:

• qt6_add_library
• qt6_finalize_target
• qt6_enable_import_plugins_finalizer_mode
• qt6_enable_resource_objects_finalizer_mode
• qt6_wasm_add_target_helpers

Existing public API in Qt6CoreMacros.cmake:

• qt6_add_executable
• qt6_add_plugin
• qt_finalize_executable

New public API in Qt6QmlMacros.cmake:

• qt6_target_qml_sources

Existing public API in Qt6QmlMacros.cmake:

• qt6_add_qml_module
• qt6_import_qml_plugins
• qt6_qml_type_registration

New public API in Qt6AxContainerMacros.cmake:

• qt6_target_typelibs

New public API in Qt6AxServerMacros.cmake:

• qt6_add_axserver_executable
• qt6_add_axserver_library
• qt6_target_idl

New public API in Qt6LinguistToolsMacros.cmake:

• qt6_add_lupdate
• qt6_add_lrelease
• qt6_add_translations

New public API in Qt6Quick3DMacros.cmake:

• qt6_quick3d_bake_lightprobe_hdri
• qt6_quick3d_internal_bake_lightprobe_hdri

Existing public API in Qt6ScxmlMacros.cmake:

• qt6_add_statecharts

Existing public API in Qt6WaylandClientMacros.cmake:

• qt6_generate_wayland_protocol_client_sources

Existing public API in Qt6WaylandCompositorMacros.cmake:

• qt6_generate_wayland_protocol_server_sources

Existing public API in Qt6RemoteObjectsMacros.cmake:

• qt6_add_repc_sources
• qt6_add_repc_replicas

New public API in Qt6ShaderToolsMacros.cmake:

• qt6_add_shaders_impl
• qt_internal_add_shaders

Existing public API in Qt6ShaderToolsMacros.cmake:

• qt6_add_shaders