[TECHNICAL REQUEST] LPS-50578 Changing language is impossible on pages like terms_of_use

Hi Tomáš,

it's the continuation of the https://github.com/topolik/liferay-portal/pull/99 pull request. A whitelist handling process has been implemented.

We though that we have a portlet request interruption handling ( so we used that name) here since we are at a point where the system is interrupting the portlet request because of some state in the system. It's that the user hasn't accepted the terms of use in this case, however, it can be handled as a bit more general pattern.

Because of this, and to have a bit more general whitelist handling pattern we are using an abstract class also. In this way a new implementation cal is needed whit simply define the properties which should be handled when a new whitelist handling is necessary.

Basically, we used the existing whitelist handling processes in the system and we put the classes to the com.liferay.portal.security.auth, however, we are not sure it that is the best place for those.

Let us know, if you have any questions.

Thank you in advance,
Zsigmond