Updated packaging for multiple connectors

[planetf1]

This change proposes improvements to build packaging as per odpi/egeria-connector-jdbc#13

• Refactored top level gradle file, similar to changes I've recently made to egeria - hopefully simpler/clearer
• Dependency constraints are primarily via an import of the egeria BOM
• docker build removed -- our charts support dynamic loading of connector jars. No longer needed/adds complexity
• updates org.odpi* dependencies to 'compileOnly' -- since they are already within the egeria platform, prevents them getting included in any uber jars we might have in future (technically slf4* qualifies too, but I left this for clarity?)
• Artifact published by build action updated with new name (as it's a combination of all 3 connectors)
• Added a few validators to ensure dependencies are in sync, and no clashes on capabilities
• removes aggregate javadocs (not used)
• deleted rogue text file

Tested

• ./gradlew build -> builds as usual
• ./gradlew ./gradlew PublishToMavenLocal -> creates local maven artifacts

I can't fully test the ci/cd publishing of snapshots until this is merged -- and may then need a few iterations.

I suggest this for review -- and if ok I will then check the end-end snapshot publishing & update

[planetf1]

@dwolfson -- here's a first pass at the approach to fix up the build process fully for our multiple connectors
@lcpopa -- hoping this doesn't break anything .... I've not tested the runtime

[sonatype-lift]

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