[desktop-lite] - Adding support for noVnc latest version in the feature

[Kaniska (Kaniska244)]

Ref: #1393

Description: This PR aims to solve #1393 by adding support for latest noVnc version. All the noVnc versions post 1.2.0 are currently not working with the desktop-lite feature due to unavailability of launch.sh script which is responsible for launching the noVnc client. In these higher versions of noVnc client post 1.2.0, the client is required to be started using novnc_proxy utility. Changes are done for adding that support & also ensured that support for the older noVnc clients(<=1.2.0) remain as-is.

Changlog: The following changes are done.

• Changed the code in install.sh to add support for noVnc client versions higher that 1.2.0
• Updated the devcontainer-feature.json to do version bump & pining the noVncVersion property to the latest 1.6.0 version.
• Added a test for the older versions(<=1.2.0) separately.

Checklist:

• All checks are passed.