meta-ohos-demo: Introduce layer

Signed-off-by: Andrei Gherzan <andrei.gherzan@huawei.com>

meta-ohos-demo/README.md

+# Introduction
+
+## Description
+
+This layer, `meta-ohos-demo`, contains build metadata for OpenHarmony demos.
+
+## Layer dependencies
+
+The `meta-ohos-demo` layer depends on the following layers:
+
+* meta-ohos
+  * URI: https://git.ostc-eu.org/OSTC/OHOS/meta-ohos.git
+* meta-homeassistant
+  * URI: https://github.com/meta-homeassistant/meta-homeassistant.git
+
+Note that the dependencies of the above layers should also be taken into
+consideration.
+
+# Contributing
+
+## Merge requests
+
+All contributions are to be handled as merge requests in the [meta-ohos Gitlab project](https://git.ostc-eu.org/OSTC/OHOS/meta-ohos).
+
+## Maintainers
+
+* Andrei Gherzan <andrei.gherzan@huawei.com>
+
+# License
+
+The license of this layer is [Apache-2.0](https://git.ostc-eu.org/OSTC/OHOS/meta-ohos/-/blob/stable/LICENSES/Apache-2.0.txt).

meta-ohos-demo/conf/layer.conf

+# We have a conf and classes directory, add to BBPATH
+BBPATH .= ":${LAYERDIR}"
+
+# We have recipes-* directories, add to BBFILES
+BBFILES += "${LAYERDIR}/recipes-*/*/*.bb \
+            ${LAYERDIR}/recipes-*/*/*.bbappend"
+
+BBFILE_COLLECTIONS += "meta-ohos-demos"
+BBFILE_PATTERN_meta-ohos-demos = "^${LAYERDIR}/"
+BBFILE_PRIORITY_meta-ohos-demos = "6"
+
+LAYERDEPENDS_meta-ohos-demos = "core"
+LAYERSERIES_COMPAT_meta-ohos-demos = "dunfell"