Select only specifically-marked Filters for CustomFilterAdapterConfiguration

aaa-filterchain monitors the OSGi registry for servlet filters being added and routes them to CustomFilterAdapter. As demonstrated by AAA-235 this can lead to confusion, as filters may be published for other purposes as well.

Introduce a well-known property name, "org.opendaylight.aaa.filterchain.filter", which needs to be set to "true" on any published filter for it to be selected by CustomFilterAdapterConfigurationImpl.