StringPatternAnonymizer - Alternative configuration proposal

[SimonMellerin]

For advanced cases, it could be nice to accept this kind of conf for the StringPatternAnonymizer:

anonymization:
    default:
        customer:a
            biography:
                anonymizer: pattern
                options: 
                     value: '{1} {2} has email address {3}.'
                     1: firstname
                     2: lastname
                     3: 
                         anonymizer: email
                         options: {domain: 'custom-domain.com'}

Originally posted by @SimonMellerin in #224 (review)