Configuring UART pins does not change hardware interface used

[Gadgetoid]

I had to dip into cdc_uart.c and change uart1 to uart0 since I wanted to use pins 0 and 1 on the board I was using as a debugger.

There should probably be a define for this in picoprobe_config.h

Also- can we get some kind of indicator LED support or hook to customise one? The board I'm using has an RGB LED onboard and I'm basically toggling a LED element in probe_handle_read and probe_handle_write which gives me some "I'm alive" indication, though it's a little rough around the edges.

P.S. this is awesome!