[nxp][examples][common] Make button components configurable (#36077)
Introduce the following flags:
- CONFIG_APP_BUTTON_ENABLED - flag to configure if ButtonApp instance is registered.
- CONFIG_BLE_BUTTON_ENABLED - flag to configure if ButtonBle instance is registered.
- CONFIG_APP_BUTTON_HANDLE_SDK_PREDEFINED - flag to configure if the button handle
is predefined in the SDK or not. If not set, the handle will be defined and initialized
explicitly in the file.
Signed-off-by: marius-alex-tache <marius.tache@nxp.com>