Allow AMP on relative paths

[petrsvihlik]

Currently, the AMP pages can be located only on different domains or subdomains.
original: http://domain.tld/my-blogpost
amp: http://amp.domain.tld/my-blogpost
alt amp: http://different.tld/my-blogpost

It should be possible to set it up so that the AMP pages are served from the same domain as where the original content is located.

original: http://domain.tld/my-blogpost
amp: http://domain.tld/amp/my-blogpost
alternatively: http://domain.tld/my-blogpost/amp

• GetFilterState() method needs to be adjusted.
• verify that the AMP link is being generated correctly

Related to #4

[ponsss]

Does it actually work on relative path like http://domain.tld/amp/my-blogpost? And if so, how to configure it?

[petrsvihlik]

@Kentico/platform-team could you guys please advise?