If 'name' is identical to 'artifactId' and 'packaging' has the default
value 'jar', we can just remove those tags from the POM.

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

Notably, this change involves a partial revert of @4a5660b3, because we
are not using JUnit Jupiter yet but still JUnit 4 tests. See discussion
under commit at https://github.com/eclipse/org.aspectj/commit/4a5660b3.

Many other warnings - concerning both used undeclared and unused
declared dependencies - were eliminated by adding or removing the
corresponding dependencies from the POMs. Furthermore, I tried to make
sure that some clearly test-scoped dependencies are now actually
declared as such, so as to avoid unwanted transitivity bleeding into
compile scope and maybe unwanted classes ending up in uber JARs via
Maven Shade or Maven Assembly.

TODO: I am not so sure why modules other than 'run-all-unit-tests' would
depend on test JARs. I hope I broke nothing essential there. As of
today, the other modules where I found '<type>test-jar</type>'
dependencies are:
  - ajde
  - testing
  - testing-drivers
  - tests
  - weaver

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

In two places, the documentation now contains this text:

"Since AspectJ 1.9.7, the obsolete Oracle/BEA JRockit agent is no longer
part of AspectJ. JRockit JDK never supported Java versions higher than
1.6. Several JRockit JVM features are now part of HotSpot and tools like
Mission Control available for OpenJDK and Oracle JDK."

The decision to drop JRockit support was made during a discussion
between Alexander Kriegisch and Andy Clement:

Andy Clement wrote on 26 Mar 2021:

> Yes I think so.
>
>
> Alexander Kriegisch wrote on 26 Mar 2021:
>
>> https://en.wikipedia.org/wiki/JRockit
>>
>> Can we get rid of that? AspectJ requires Java 8, JRockit never
>> supported more than Java 6.

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

It was the only subdirectory under lib/ext anyway and somehow always
irritating and difficult to find when just using a directory browser in
the IDE.

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

Signed-off-by: Lars Grefer <eclipse@larsgrefer.de>