Add UART RTS and CTS to M.2 board tests and gateware version in overlays' "chosen" entry
- Allow the control of M2_UART_RTS and M2_UART_CTS from the CorePGIO instance used for board tests of the M.2 connector.
- Insert the gateware's git version into the overlays' device tree "chosen" entry.
- Correct cape's GPIO option readme pin description.