Add battery option for RearViewsion kits.

[truedat101]

Batteries and charging batteries are somewhat essential. Add some kit options for:

• battery with holder
• diy battery
• fuel gauge

[truedat101]

For the ESP32-CAM, review: https://arduino.stackexchange.com/questions/77844/powering-an-esp32cam-by-a-battery

[truedat101]

m5stack has some options to hold batteries. I will try these.

[truedat101]

So in general for the M5Stack cams, I found a discussion on this topic:
https://community.m5stack.com/topic/377/external-power-what-is-possible/15

Generally the answer was:

• USB power supply
• make your own
• use the battery unit for M5

Someone suggested making a custom board out of

https://docs.m5stack.com/en/unit/proto

I managed to find 3 options on the M5 store that are newer: https://docs.m5stack.com/en/accessory/Grove2USB-C https://docs.m5stack.com/en/atom/tailbat

There's one other case with a battery I found from M5. All in all these are all viable options.