Externalizer does not map paths according to resolver mappings

[HitmanInWis]

The Externalizer in AEM Mock does not honor resource resolver mappings, whereas it does on a running AEM server.

As an example if I have a resource resolver mapping of /content/mysite/abc:/custompath

• Calling resourceResolver.map("/content/mysite/abc/page") returns /custompath/page as expected
• Calling externalizer.publishLink(resourceResolver, "/content/mysite/abc/page") should return <domain>/custompath/page but instead it returns <domain>/content/mysite/abc/page

This creates a situation where tests have to check for an externalized URL string that is not actually what we expect on the running server.

[stefanseifert]

implemented with #45

[HitmanInWis]

Amazing response time :D Thanks!