Make EMA parameters configurable

[jmcollin78]

Auto window open detection use the EMA calculation introduced for regulation.

Because some configuration need more smoothing into the EMA calculation, the default parameter should be easily updated.
Because the VTHerm configuration process is aleady complex, we need to add this parameters into the optional configuration.yaml introduced with auto regulation feature.

The parameters are:

1. MAX_ALPHA: a parameter that limits the alpha influence (ir the weight of a measurement point depending of its delay vs the previous one),
2. halflife: the length of the period in which we consider the old values
3. precision: the number of digits of precision

[jmcollin78]

Example of configuration (which correspond to the default configuration):

versatile_thermostat:
    auto_regulation_expert:
        kp: 0.4
        ki: 0.08
        k_ext: 0.0
        offset_max: 5
        stabilization_threshold: 0.1
        accumulated_error_threshold: 50
    short_ema_params:
        max_alpha: 0.5
        halflife_sec: 300
        precision: 2