Improve solar yield widget on the Overview page

[jpetrell]

Reported by the customer:

• "I still hope that the solar graph would be much more detailed, scientific as that's what eveyone is eyeballing constantly."
• "Also, am I wrong in saying that the solar graph only shows the history as far as the gui has been running? That's ought to change I presume."

Also here:

• "Couls you please add: 2. Show more details (Currant, Voltage) at "Overview" for Solar- like at battery"

[mr-manuel]

Also note this comment https://github.com/victronenergy/gui-v2/issues/513#issuecomment-2081158971