Dual control mode - valve OR output control

[tetele]

I was wondering whether it would be a good idea to pick from one of two mutually exclusive operating modes:

• valve on/off control (the current mode)
• output control - control the output value on a 0-100 scale

I have an ESPHome valve controller which would greatly benefit from having manual control in case HA, wifi or Zigbee is down for some reason (especially when they are down intermittently). To do this, I'd like to expose a bunch of numbers from ESPHome, each controlling a slow PWM signal for one heating coil. Internally, ESPHome would handle the turning on/off of valves based on that PWM signal.

In this particular case, the PID thermostat would not have access to a switch/valve, but rather dictate what width the PWM controller should output, in sync with the climate entity's control_output attribute. That value would be assigned to a single number entity exposed by ESPHome.

If I ever needed manual control for some reason, the ESPHome device would simply follow a default PWM fill rate, not dictated by the thermostat.

When controlling just the output, there would be no control of actual heater actuator.

If this idea is approved, I can contribute with the actual implementation.

Possibly related to #173

[tetele]

Partially solved in #248

The PR adds support for the valve.set_valve_position service being called every time the control output should modify a numeric output (like it did for light, number and input_number).