Initial design for hatlet and hatlet-dongle

[chiplet]

Adds the following boards:

hatlet 0.1.0

hatlet is a small RP2040 dev board that:

• breaks out most of RP2040 the peripherals to PMOD female headers
• uses the racklet backplane header for power input and USB communication.

hatlet-dongle 0.1.0

hatlet-dongle is a small adapter board that allows you to connect a hatlet to a development host PC without a full backplane. In essence, it is a backplane-side breakout board of the racklet backplane connector with:

• USB type C connector for D+/D- and +5VSB power input,
• Banana jacks for SBC supplies (+12V, +5V), management power supply (+5VSB), and ground.
  The +5VSB source can be chosen between the type C connector and banana jack with a jumper.