change switch icon to use toggle-switch(-off)

[Mariusthvdb]

followup on https://discord.com/channels/330944238910963714/460846676358332417/903580422993248287 please concider change the current mdi:flash icon used for domain Switch

frontend/src/common/const.ts

Line 107 in 4624c3d

switch: mdiFlash,

to use mdi:toggle-switch.

mdi:flash is more suitable and used on power devices, and not really related to a switching device at all.

using mdi:toggle-switch would also allow the device_class switch to set mdi:toggle-switch-off in the 'off' state obviously.

thanks for considering