Add ONVIF bicep files

[dominicbetts]

Purpose

• Add ONVIF bicep files to support how-to article: https://learn.microsoft.com/en-us/azure/iot-operations/discover-manage-assets/howto-use-onvif-connector

Does this introduce a breaking change?

[ ] Yes
[x] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[x] Documentation content changes
[ ] Other... Please describe: