Support set_ps for yeelink lamp nightlight mode 请支持床头灯夜灯模式

[manymuch]

Please either

1. add set_ps method like xiaomi_miot
   or
2. Support nightlight mode for yeelink.light.bslamp2

For example, here is the action command to trigger nightlight mode in xiaomi_miot

action: xiaomi_miot.send_command
data:
  entity_id: light.yeelink_bslamp2_b51b_light
  method: set_ps
  params:
    - nightlight
    - 'on'