Add user notes to sensor settings

[markoaamunkajo]

Description:

Add user notes section under General as the last item.
Show popup same as when user changes sensor name when user taps on pen icon.
Make this sync between devices through cloud.

Only owner can edit notes, sharee will be able to see but cannot edit notes

1000 characters limit

Editor must support enter and line breaks

iOS card: ruuvi/com.ruuvi.station.ios#1870

Use same description font as under signal strength.

[andreevdenis]

Waiting for cloud API implementation