Convert public services to OSGi DS

Convert public services to OSGi DS

In order to unblock users, convert ODLAuthenticator and
ShiroWebContextSecurer into Declarative Services components.

Since we still rely on blueprint to pick up configuration and aaa-cert
services, bridge these two worlds by publishing WebEnvironment via an
implementation-specific AAAShiroWebEnvironment.

This also forces WebInitializer to be a proper component, as otherwise
we would have a circular dependency its WebContextSecurer dependency.

Since not all our services are SCR components, we need to explictly list
out our Provide-Capability entries.

JIRA: AAA-251
Change-Id: Ia5a0d28e10d7597a9c5fe90c3cf084c25da652a9
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>