hil: add ea4088_quickstart with an RTT console

The board's probe is an LPC-Link2 with no VCOM, so its console is RTT. Two
host tests could not run that way: test_host_cdc_msc_hid and
test_host_msc_file_explorer opened the flasher's VCOM directly instead of
going through open_board_console(), and the config gate rejecting
is_cdc/is_msc fixtures on "logger": "rtt" boards existed only to keep them
from dying mid-run on a port that does not exist.

Route both through the console abstraction and drop the gate. The reset
ordering differs per console -- RTT owns the probe so the board must be reset
before the console opens, a VCOM survives the reset so it opens first -- and
that rule now lives in open_console_reset() instead of being spelled out at
each call site.

The roster entry runs device, host and dual: USB1's Type-A drives a hub with
a CH340 (TX-RX shorted, for the cdc echo) and a thumbdrive, while USB2 keeps
serving the device tests. BUFFER_SIZE_DOWN=128 because that echo writes up to
64 bytes at once and SEGGER's ring keeps one byte free, which the 16-byte
default cannot hold; 64 measured unreliable, 128 reliable.

Measured on the rig: 19 passed, 0 failed, 0 skipped. usbtest 30/30, host MSC
reads 682 KB/s, device CDC/MSC ~510 kB/s (full speed behind the rig's hub).