Target alias

[JaSei]

What does this do?

Some targets (Influx for example) use alias instead of legendFormat (which is Prometheus "alias"). This commit setup both of them by current legendFormat.

Why is it a good idea?

For Influxdb SqlTarget isn't now possible to set "alias" via Target. Of course is possible to use InfluxDBTarget (https://github.com/weaveworks/grafanalib/blob/main/grafanalib/influxdb.py) but there missing other options (like hide, because it's not child of Target). So I've chosen solution to extend Target to support all needed for my influx.

Context

Questions

If you don't like this solution, I see other solutions

1. add new alias option - similar as Add support for alias expressions in data targets #285
2. InfluxDBTarget class should be inherit from Target