Deprecate quarkus-bootstrap-maven-plugin in favor of quarkus-extension-maven-plugin

[aloubyansky]

The quarkus-bootstrap-maven-plugin includes a single goal extension-descriptor which is used in extension projects to generate extension metadata, etc. I thought it would make more sense to have a more appropriate artifactId for the plugin.

This PR deprecates the quarkus-bootstrap-maven-plugin and updates everything (the extension POMs, docs, project templates and tests) to use quarkus-extension-maven-plugin instead.

[rsvoboda]

@aloubyansky feels like noteworthy label candidate

[aloubyansky]

Thanks @rsvoboda

[rsvoboda]

there is one side-effect to this change, only people using quarkus cli from quarkus main would notice

qss -version                                                                                                                            ✔  11:10:03 
999-SNAPSHOT

qss create extension ext
cd quarkus-ext
mvn clean package

[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary for Quarkus - Ext - Parent 1.0.0-SNAPSHOT:
[INFO]
[INFO] Quarkus - Ext - Parent ............................. SUCCESS [  2.060 s]
[INFO] Quarkus - Ext - Runtime ............................ FAILURE [  2.004 s]
[INFO] Quarkus - Ext - Deployment ......................... SKIPPED
[INFO] Quarkus - Ext - Integration Tests .................. SKIPPED
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  4.345 s
[INFO] Finished at: 2022-06-08T11:09:02+02:00
[INFO] ------------------------------------------------------------------------
[ERROR] Plugin io.quarkus:quarkus-extension-maven-plugin:2.9.2.Final or one of its dependencies could not be resolved: Could not find artifact io.quarkus:quarkus-extension-maven-plugin:jar:2.9.2.Final in jboss-public-repository (https://repository.jboss.org/nexus/content/groups/public/) -> [Help 1]

It's because the version of CLI defines what code-starters get applied and the registry defines what (released) version gets used.
So the 999-SNAPSHOT based CLI forces extension which is not available in 2.9.2.Final release.

[aloubyansky]

We should probably add a version check in the templates. If the quarkus version is older than 2.10.0 it should be the bootstrap plugin. Thanks for noticing @rsvoboda