More JAR/WAR containerization support

Creating an umbrella issue to track various issues and feature requests related to JAR/WAR containerization.

* #1852 support fat/shaded JAR
- An alternative is to have some means to exclude dependency JARs.
* #530 runnable JAR with `java -jar`
- Most often fat JAR in practice but does not rule out slim JAR.
- There seem use case where `java -jar` is useful where `java -cp` can't cover.
* #1555 Jib with Quarkus
- Perhaps `java -jar` is really needed here. (#530)

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* #1859: command line tool to jib a JAR/WAR
* #1851 bootJar if Spring Boot?
- Being a fat JAR, may depend on #1852.
- Similarly in #1786.
- Has a workaround.
- Or more generally, have a way to configure a JAR task or path, or infer this automatically (applies to Maven too).
- #1606 involves using `classifier` in the Spring Boot plugin.
* #1470 (low priority): get `Main-Class` from `MANIFEST.MF` from JAR

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FTR, duplicates closed:
- #1280 Thorntail / Payara Micro example
- #1194 Thorntail