Add CI on Zephyr (#4336)

to run product-mini/platforms/zephyr/simple and
product-mini/platforms/zephyr/user-mode

Construct a T2 (star topology) for the current smoke test. This is not the
final topology, and we may modify it once we determine the optimal
configuration.

.github/scripts/run_qemu_arc.sh

@@ -0,0 +1,46 @@
+#!/bin/bash
+
+# THIS SCRIPT IS USED TO RUN QEMU ARC EMULATOR DIRECTLY ON CI ONLY.
+# USUALLY, you SHOULD NOT RUN IT ON YOUR LOCAL MACHINE.
+# INSTEAD, YOU SHOULD USE `west build -t run` COMMAND.
+
+# Two arguments. first is the path to the zephyr-sdk, second is the path to the zephyr elf.
+if [ "$#" -ne 2 ]; then
+    echo "Usage: $0 <path_to_zephyr_sdk> <path_to_zephyr_elf>"
+    exit 1
+fi
+
+ZEPHYR_SDK_PATH=$1
+ZEPHYR_ELF_PATH=$2
+
+if [ ! -d "$ZEPHYR_SDK_PATH" ]; then
+    echo "Error: Zephyr SDK path does not exist: $ZEPHYR_SDK_PATH"
+    exit 1
+fi
+if [ ! -f "$ZEPHYR_ELF_PATH" ]; then
+    echo "Error: Zephyr ELF file does not exist: $ZEPHYR_ELF_PATH"
+    exit 1
+fi
+
+# this command is copied from the content of build.ninja which is generated by west build.
+# please do not modify it unless synchronizing with the build.ninja file.
+$ZEPHYR_SDK_PATH/sysroots/x86_64-pokysdk-linux/usr/bin/qemu-system-arc \
+  -cpu arcem -m 8M \
+  -nographic -no-reboot -monitor none \
+  -global cpu.firq=false \
+  -global cpu.num-irqlevels=15 \
+  -global cpu.num-irq=25 \
+  -global cpu.ext-irq=20 \
+  -global cpu.freq_hz=10000000 \
+  -global cpu.timer0=true \
+  -global cpu.timer1=true \
+  -global cpu.has-mpu=true \
+  -global cpu.mpu-numreg=16 \
+  -net none \
+  -pidfile qemu.pid \
+  -chardev stdio,id=con,mux=on \
+  -serial chardev:con \
+  -mon chardev=con,mode=readline \
+  -icount shift=6,align=off,sleep=off \
+  -rtc clock=vm \
+  -kernel $ZEPHYR_ELF_PATH