[NEXUS-5971] remove use of ExtensionPoint
Remove deprecated index related classes.
Moving compat to depend on core
Tearing down compat

Leaving events only for now
Merge remote-tracking branch 'origin/NEXUS-5971-remove-managed-extensionpoint' into remove-deprecated-classes
Events redirected.

This change affects only EventInspectors! All the other EventBus users
subscribers are still safe
Remove deprecated classes.
Remove nexus-compat module
Merge remote-tracking branch 'origin/master' into remove-deprecated-classes

Conflicts:
	components/nexus-compat/pom.xml
	components/nexus-compat/src/main/java/org/sonatype/nexus/compat/EventBusApplicationEventMulticaster.java
	components/nexus-core/src/main/java/org/sonatype/guice/nexus/scanners/NexusTypeCache.java
	components/nexus-core/src/main/java/org/sonatype/guice/nexus/scanners/NexusTypeVisitor.java
	components/nexus-core/src/main/java/org/sonatype/nexus/error/reporting/SetProxyPropertiesInspector.java
	components/nexus-core/src/main/java/org/sonatype/nexus/events/DebugEventInspector.java
	components/nexus-core/src/main/java/org/sonatype/nexus/events/DefaultEventInspectorHost.java
	components/nexus-core/src/main/java/org/sonatype/nexus/index/events/ReindexRepositoriesEvent.java
	components/nexus-core/src/main/java/org/sonatype/nexus/index/events/ReindexRepositoriesRequest.java
	components/nexus-core/src/main/java/org/sonatype/nexus/proxy/attributes/StorageFileItemInspector.java
	components/nexus-core/src/main/java/org/sonatype/nexus/proxy/events/AsynchronousEventInspectorWrapper.java
	components/nexus-core/src/main/java/org/sonatype/nexus/proxy/events/EventInspector.java
	components/nexus-core/src/main/java/org/sonatype/nexus/scheduling/NexusTaskFailureErrorManagerReporter.java
	components/nexus-core/src/main/java/org/sonatype/nexus/util/StringDigester.java
	components/nexus-core/src/test/java/org/sonatype/nexus/events/DefaultEventInspectorHostTest.java
	components/nexus-core/src/test/java/org/sonatype/nexus/proxy/AbstractProxyTestEnvironment.java
	plugins/internal/nexus-wonderland-plugin/src/main/resources/static/js/Nexus/wonderland/Icons.js
	plugins/internal/nexus-wonderland-plugin/src/main/resources/static/js/nexus-wonderland-plugin-boot.js
	plugins/maven/nexus-archetype-plugin/src/main/java/org/sonatype/nexus/plugins/mac/MacPluginEventSubscriber.java
Removed deprecated cruft
Applied removals of deprecations
Merge remote-tracking branch 'origin/master' into NEXUS-6027-remove-deprecated-classes
NEXUS-6099: Remove attribute upgraders
NEXUS-6027: remove EventInspectors

Replaced with EventSubs
Merge remote-tracking branch 'origin/master' into NEXUS-6027-remove-deprecated-classes

Conflicts:
	components/nexus-core/src/main/java/org/sonatype/nexus/events/DefaultEventInspectorHost.java
	components/nexus-core/src/main/java/org/sonatype/nexus/events/DefaultVetoFormatter.java
	components/nexus-core/src/main/java/org/sonatype/nexus/events/EventSubscriberHost.java
	components/nexus-core/src/main/java/org/sonatype/nexus/plugins/events/PluginDeactivatedEvent.java
	components/nexus-core/src/main/java/org/sonatype/nexus/proxy/attributes/AbstractStorageFileItemInspector.java
	components/nexus-core/src/main/java/org/sonatype/nexus/proxy/attributes/DefaultAttributesHandler.java
	components/nexus-core/src/main/java/org/sonatype/nexus/proxy/attributes/DefaultFSAttributeStorage.java
	components/nexus-core/src/main/java/org/sonatype/nexus/proxy/attributes/LegacyFSAttributeStorage.java
	components/nexus-core/src/main/java/org/sonatype/nexus/proxy/attributes/upgrade/DefaultAttributeUpgrader.java
	plugins/p2/nexus-p2-repository-plugin/src/main/java/org/sonatype/nexus/plugins/p2/repository/internal/GlobalRemoteProxySettingsInspector.java
NEXUS-6027: Cleanup after removal of EIs
NEXUS-6027: Lost one event during conversion
NEXUS-6027: Subscriber host must not be eager singleton

At least in tests, it has to share same lifecycle as
NxApplication, as otherwise all the UTs would "boot" almost
all of the object graph of Nexus
NEXUS-6027: Fixing UT, that used inspector
NEXUS-6027: Fixing EventSubscriberHost

Simplified it, as original mediator use was not appropriate
as it was "loosing" subscribers, leaving system in limbo.
as it tried to get the component instances too early (during
their discovery).