Add API for determining update rate from sensors and make Line Chart face have only an "amount of history" in its config

This adds API to determine the update rate of sensors and similar things so we do not need to hardcode those in the UI. In addition, it contains a change to make the Line Chart face determine the amount of items to keep based on a single setting of how much history to keep in seconds, since specifying the amount of items to keep is tricky as that depends on the update rate.

Depends on frameworks/kquickcharts!26 (merged)