Slim modular Raspberry Pi Pico Case Mod

It's for the Pico W.

Changes to the original one:

- Access to the SWD pins
- More height to insert a 300mAh LiPo battery with JST2.0 connector
- LiPo is tighened with the screw holes
- A bottom enclosure for housing the BMS ySemi XB8089D
- Advantage of the bottom enclosure, the SWD-Pins, button and LED is on the front side

I've done several power profiling tests with the DS3231 board. There are two deepsleep modes: sleep and dormant. Dormant is slighlty better, but with the DS3231 board attached, it doesn't make a huge difference.

Thanks a lot to maximilliampere, who is the initial designer of this enclosure.