Custom scriptlets and redirect resources

See the details here: https://github.com/AdguardTeam/CoreLibs/issues/1225

Basically, we need a way to supply custom redirect and scriptlet resources, that can then be used in normal scriptlet/redirect rules.

Once this task is completed, we should file additional tasks to the product repos so that this setting could be exposed via low-level flags.

A simple solution would be to allow people to supply custom map with scriptlets/redirect resources. This would require modifying and building Scriptlets repo.