Rework binding component instantiation

Rework binding component instantiation

This reshuffles how DOM and Binding interoperate where schema is
concerned. Since Binding requires Classloader information available
at scanning time, we refactor mdsal-dom-schema-service-osgi to
actually perform Binding-aware scanning, so that this information
is available in ModuleInfoSnapshot.

These are published as OSGiModuleInfoSnapshot along with generation
number for easier reference by a new component, OSGiModelRuntime.

DOMSchemaService is realized on top of ServiceRegistry, where it
listens for OSGiModelRuntime and for SchemaContextListeners, driving
an OSGi whiteboard pattern.

This renders mdsal-binding-dom-codec-osgi completely superfluous,
as there is not enough magic going on to justify it.

mdsal-binding-runtime-osgi is also hooked onto OSGiModuleInfoSnapshot,
providing BindingRuntimeContexts as needed and retaining generation
inforation.

JIRA: MDSAL-392
Change-Id: I083caf3abbc3d7e2212d1df14e45d2745096b5f9
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>