Improve alarm & event rendering when multiple datapoints are shown

[haraldmeyer]

Is your feature request related to a problem? Please describe.
When multiple datapoints are shown, the alarm / event is attached to the first datapoint (whichever that might be). When that datapoint is disabled the alarm/event jumps to the next active datapoint.

Describe the solution you'd like
It should be possible to select to which (or none) datapoint an alarm/event belongs and it should always be shown on the line corresponding to that datapoint. If the datapoint is disabled the alarm should be shown directly on the x-axis.

[janhommes]

Idea is:

Showing a dropdown where you can select the datapoint the alarm icon should be shown. Should auto-select the one where the source matches. If none matches, "top" is selected and the alarm is shown on top.