Add scheduled service API and XML actions

[moqui-industrial]

Adds a scheduled service API, XML actions for scheduling and cancellation, and configuration support for an optional distributed scheduled executor.

Files changed:

• framework/src/main/groovy/org/moqui/impl/service/ServiceFacadeImpl.groovy
• framework/src/main/groovy/org/moqui/impl/service/ServiceCallScheduledImpl.groovy
• framework/src/main/java/org/moqui/service/ServiceFacade.java
• framework/src/main/java/org/moqui/service/ServiceCallScheduled.java
• framework/template/XmlActions.groovy.ftl
• framework/xsd/moqui-conf-3.xsd
• framework/xsd/xml-actions-3.xsd
• framework/src/main/resources/MoquiDefaultConf.xml

Validation performed:

• git diff --check
• xmllint --noout on changed XSD/XML files
• ./gradlew framework:compileJava framework:compileGroovy framework:testClasses

This PR supersedes #719.