Chart widget - 2 y-axis's

[Paul-Reed]

This was discussed several times in the early stages of DB2, but it appears not to be recorded as a git issue. (My fault! - https://discourse.nodered.org/t/dashboard-2-beta-development/83550/119)
I'm in the process of switching from Flexdash to DB2, but my development stalled some months ago due to not being able to utilise scaleable left & right y-axis for some of my charts.
For example one such chart monitors the performance of a solar energy diverter, and whose temperature data is recorded on the left axis, whilst power data is recorded on the right data.
I can then monitor the effects of high energy diversion, against its operating temperature.
I've taken a quick screenshot of my Flexdash dash, and note the scaling and unit suffix is different left & right axis.

Could we please add this feature to DB2.

[Paul-Reed]

Apologies - duplicate of #752 #296 & #58