Vidos resolver example

[toteto]

This PR adds Vidos as optional resolver that can be used in verify DID examples.

Implementation overview

• VidosResolver is an example implementation of Resolvable that uses Vidos resolver instance as resolution mechanism.
• The configuration is being made via the .env file, the .env.example is updated with placeholder variable names.
• The creation of the didResolver has been moved to createDidResolver that creates the most appropriate resolver for the given configuration. This will create the VidosResolver if there is Vidos configuration, otherwise the regular Onyx resolver via the getSupportedResolvers helper method. This method returns object of the resolver and the methods in order for future expansions in the examples to be able to use these objects.

Other

I have accepted the contribution CLA and have send it, as described in https://github.com/jpmorganchase/onyx-ssi-sdk-examples/blob/main/CONTRIBUTING.md