boards: mikroe: add initial support for Mikroe RA4M1 Clicker

The RA4M1 Clicker is a basic development board for the Renesas RA4M1
Microcontroller. The board contains J-Link on board, two LEDs and push
buttons and several headers for interfacing with external devices.

Signed-off-by: Ian Morris <ian.d.morris@outlook.com>