Add Vue 3 sample to getting started code sample

[dichotommy]

The getting_started_front_end_integration_md code sample is currently only compatible with Vue 2. We should also provide code accomplishing the same thing that works with Vue 3. This code can be added within the same sample, above or below the current content.

[bidoubiwa]

The code sample provided here should be recreated but in a html environment and not a .vue one. See example here for vue2