environment: transfer and adapt Env and SenseEnv from physic into Weather and SenseWeather

As part of this work, make it use context.Context.

The addition of the new packages can be done seamlessly in v3.5.0, but the removal of physic.Env and physic.SenseEnv is a breaking change.

If the new methods are named SenseWeather() and SenseWeatherContinuous(), we can have the driver supports both for v3.5.0 which will be less disruptive for users.

Ported to https://github.com/periph/conn/issues/28.