avahi: Add HDC service file for DNS-SD/mDNS discovery

To discover the targets IP address and HDC service running on
it we offer a avahi service file.

An example command on the host to discover it would be:
avahi-browse _workstation._tcp --terminate -r

Signed-off-by: Stefan Schmidt <stefan.schmidt@huawei.com>

recipes-connectivity/avahi/avahi/hdc.service

+<?xml version="1.0" standalone='no'?><!--*-nxml-*-->
+<!DOCTYPE service-group SYSTEM "avahi-service.dtd">
+<service-group>
+<name replace-wildcards="yes">OpenHarmony Device Connector on %h</name>
+<service>
+<type>_workstation._tcp</type>
+<port>35000</port>
+</service>
+</service-group>

recipes-connectivity/avahi/avahi_%s.bbappend

+# SPDX-FileCopyrightText: Huawei Inc.
+#
+# SPDX-License-Identifier: MIT
+
+FILESEXTRAPATHS:prepend := "${THISDIR}/${PN}:"
+
+SRC_URI:append = "file://hdc.service"
+
+do_install:append () {
+    install -d ${D}${sysconfdir}/avahi/services/
+    install -m 0644 -g avahi ${WORKDIR}/hdc.service ${D}${sysconfdir}/avahi/services/hdc.service
+}

recipes-openharmony/images/openharmony-standard-image.bb

@@ -13,3 +13,6 @@ IMAGE_INSTALL += "openharmony-standard"
 
 # Let's be friendly enough to provide a fully working interactive shell
 IMAGE_INSTALL += "bash"
+
+# Provide avahi and a DNS-SD service file to discover the HDC service
+IMAGE_INSTALL += "avahi-daemon"