Add fallback for when the user isn't running the framework

[philipsens]

Is your feature request related to a problem? Please describe. If user is using frank-flow in standalone or as demo, the elements can't get fetched.

Describe the solution you'd like Use frankdoc.frankframework.org as fallback

• [ ] Json file
• [ ] Elements (gui)

Describe alternatives you've considered

• frank4example
• Include files

[philipsens]

The https://frankdoc.frankframework.org can be used now