Remove bi-directional dependencies between Engine and Servlets Resolver

Situation

• bundle org.apache.sling.engine requires a ServletResolver which is provided by bundle org.apache.sling.servlets.resolver
• bundle org.apache.sling.servlets.resolver depends on org.apache.sling.engine.servlets API

The bi-directional dependencies between Engine and Servlets Resolver prevent the creation of meaningful and light deployment units (testing, features).

Options

1. Merge org.apache.sling.engine and org.apache.sling.servlets.resolver into a single entity (bundle)
2. Move org.apache.sling.engine.servlets.ErrorHandler into Sling API (package org.apache.sling.api.servlets) and adjust usage in Servlets Resolver
3. Keep as is – leading to bigger, less manageable deployment units