Properly define + document JKubeProjectAssembly behavior

[manusa]

Description

As of now, JKubeProjectAssembly behavior is not aligned with Maven's Assemby Plugin behavior.

Behavior for filesets includes, excludes, filtered, etc. is opinionated and doesn't perform as described in https://maven.apache.org/plugins/maven-assembly-plugin/assembly.html#class_fileSet.
There are some fields missing too.

Same goes for file, repository, etc.

We should either properly document our API behavior or completely implement the behavior mimicking the one provided by Apache Maven Plugin.

Relates to:

• JKubeAssemblyFile.filtered ignored #87
• https://books.sonatype.com/mvnref-book/reference/assemblies-sect-basics.html
• https://books.sonatype.com/mvnref-book/reference/assemblies-sect-controlling-contents.html

[manusa]

Actions to take:

• Drop support for descriptorRef & descriptor fields which are no longer being processed since Maven decoupling took place.
• Remove these predefined assemblies (k8s / oc) since they are ignored as descriptor and descriptorRef are not considered during assembly processing.
• Remove other assemblies defined in the project which are no longer used:
  • artifact-with-includes.xml - artifact
  • java-app.xml - artifact-with-dependencies
  • webapp.xml - webapp
  • karaf.xml - karaf

fileSet - AssemblyFileSet

• Discarded properties:
  • useDefaultExcludes
  • lineEnding
  • filtered
  • nonFilteredFileExtensions
• Supported properties
  • outputDirectory
  • includes: To support java.nio.file.FileSystem#getPathMatcher glob syntax
  • excludes: To support java.nio.file.FileSystem#getPathMatcher glob syntax
  • fileMode
  • directoryMode
  • directory

file - AssemblyFile

• Discarded properties:
  • sources
  • filtered
  • lineEnding
• Supported properties
  • source
  • outputDirectory
  • destName

Possible consequences

After Maven decoupling some of the features provided by XML maven assemblies were lost and broken. Dropping this configuration fields will have no immediate consequence for JKube. However, projects migrating from FMP to JKube that made use of any of the predefined assemblies, or provided custom assemblies will be affected and will probably stop working unless their configurations are updated to be compatible with the new "Mavenless" approach.