bug fixes in virtualization and CoapClient, add virtualization tests

This MR addresses the following tasks: oniro#287 (closed) oniro#291 (closed)

• linux/CoapClient: fix token being reused after new session is created
• linux/virtualization: fix return of destroyed string
• virt_server: add exampleres flag to add mock resources
• .ci/Dockerfile: add apt install dbus and add script to run dbus-daemon
• virtualization_tests: add virtualization tests

Signed-off-by: Francesco Pham francesco.pham@huawei.com