[WELD-1309] Use required-bundles for extensions discovery and beans discovery
[WELD-1313] Avoir direct access to public static thread locals in weld-osgi and use accessors
Conflicts:
	environments/osgi/core/extension/src/main/java/org/jboss/weld/environment/osgi/impl/integration/IntegrationActivator.java
[WELD-1312] Cleaner separation between extension and integration bundles
Remove split package, remove duplicate extension definition, fix OSGi metadata (remove dynamic imports)