Provide a code start for Quarkus extension

Acceptance Criteria (Required on creation):

• There is a defined codestart for our Quarkus extension that can be downloaded and run from https://code.quarkus.io/?extension-search=origin:other%20camunda
• We create a codestart for our Quarkus extension, similar to how Kogito does it
  • https://github.com/kiegroup/kogito-runtimes/tree/main/quarkus/extensions/kogito-quarkus-decisions-extension/kogito-quarkus-decisions/src/main/codestarts/quarkus/kogito-dmn-codestart
• We adjust https://github.com/camunda/camunda-bpm-platform/blob/master/quarkus-extension/engine/runtime/ to point to a codestart, similar to how it's done in Kogito
  • https://github.com/kiegroup/kogito-runtimes/blob/main/quarkus/extensions/kogito-quarkus-decisions-extension/kogito-quarkus-decisions/src/main/resources/META-INF/quarkus-extension.yaml#L12
  • https://github.com/kiegroup/kogito-runtimes/blob/main/quarkus/extensions/kogito-quarkus-decisions-extension/kogito-quarkus-decisions/pom.xml#L46

Hints (optional):

• Downloading camunda-bpm-quarkus-engine ZIP from https://code.quarkus.io/?extension-search=origin:other%20camunda and running mvn clean verify fails with:

  Caused by: io.quarkus.builder.BuildException:
  Build failure: Build failed due to errors
  	[error]: Build step io.quarkus.agroal.deployment.AgroalProcessor#build threw an exception: io.quarkus.runtime.configuration.ConfigurationException: Unable to find a JDBC driver corresponding to the database kind 'h2' for the default datasource. Either provide a suitable JDBC driver extension, define the driver manually, or disable the JDBC datasource by adding 'quarkus.datasource.jdbc=false' to your configuration if you don't need it.
  	at io.quarkus.agroal.deployment.AgroalProcessor.resolveDriver(AgroalProcessor.java:331)
  	at io.quarkus.agroal.deployment.AgroalProcessor.getAggregatedConfigBuildItems(AgroalProcessor.java:277)
  	at io.quarkus.agroal.deployment.AgroalProcessor.build(AgroalProcessor.java:82)
  	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
  	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
  	at io.quarkus.deployment.ExtensionLoader$2.execute(ExtensionLoader.java:887)
  	at io.quarkus.builder.BuildContext.run(BuildContext.java:277)
  	at org.jboss.threads.ContextHandler$1.runWith(ContextHandler.java:18)
  	at org.jboss.threads.EnhancedQueueExecutor$Task.run(EnhancedQueueExecutor.java:2449)
  	at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1478)
  	at java.base/java.lang.Thread.run(Thread.java:829)
  	at org.jboss.threads.JBossThread.run(JBossThread.java:501)
  

• Root cause: a datasource is not configured / available
• We shouldn't change our quarkus extension to automatically pull in the h2 dependency. Going into production with a reasonable database would mean that a user has to exclude the dependency.