examples: moved app_matter apis as component at examples/matter/common
examples/matter/matter_light: renamed app_matter to app_matter_light
examples/matter/matter_light: fixed for thread
examples/matter/matter_light: moved forward declaration to app_priv.h
examples/matter/matter_switch: Updated to include app_matter as component
examples/matter/matter_controller: Updated to include app_matter as component
examples/matter/matter_controller_with_touchscreen: Updated to include app_matter as component
removed namespace declaration from header file.