RFR: 7308: Move non-Eclipse dependant classes from org.openjdk.jmc.ui.common to org.openjdk.jmc.common

[Alex Macdonald]

This PR addresses JMC-7308 [[0]](https://bugs.openjdk.java.net/browse/JMC-7308), in which it would be helpful to have some of the classes currently in jmc.ui.common shipped in core.

There are a number of classes currently in jmc.ui.common that would be a great asset to the core distribution (and the third-party applications that consume jmc-core), and these classes could live in jmc.common.

It isn't as straightforward as moving all of the packages to core, as there are still classes in these jmc.ui.common packages that have dependencies on Eclipse or rjmx. Having said that, the ones listed below can be moved without much difficulty:

- org.openjdk.jmc.ui.common.action (3)
    Executable, IActionProvider, IUserAction

- org.openjdk.jmc.ui.common.jvm (5)
    Connectable, JVMArch, JVMCommandLineToolkit, JVMDescriptor, JVMType

- org.openjdk.jmc.ui.common.resource (2)
    IImageResource, Resource

- org.openjdk.jmc.ui.common.security (10)
    ActionNotGrantedException, CredentialsNotAvailableException, FailedToSaveException, ICredentials, InMemoryCredentials, ISecurityManager, PersistentCredentials, SecurlyStoredByteArray, SecurityException, SecurityManagerFactory

- org.opendjk.jmc.ui.common.tree (3)
    IArray, IChild, IParent

- org.openjdk.jmc.ui.common.util (4)
    Environment, Filename, ICopyable, IObservable

- org.openjdk.jmc.ui.common.xydata (5)
    DataSeries, DefautlTimestampedData, DefaultXYData, ITimeStampedData, IXYData

[0] https://bugs.openjdk.java.net/browse/JMC-7308

-------------

Commit messages:
 - update license headers
 - update agent plugin imports
 - migrate classes from ui.common.resource to core
 - migrate interfaces from ui.common.action to core
 - migrate most of the remainder from ui.common.security to core
 - migrate ui.common.xydata to core
 - migrate Environment, Filename, ICopyable, and IObservable from ui.common.util to core
 - migrate ui.common.tree to core
 - migrate ui.common.jvm to core
 - ui.common.security classes to core

Changes: https://git.openjdk.java.net/jmc/pull/300/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmc&pr=300&range=00
  Issue: https://bugs.openjdk.java.net/browse/JMC-7308
  Stats: 609 lines in 173 files changed: 146 ins; 174 del; 289 mod
  Patch: https://git.openjdk.java.net/jmc/pull/300.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/300/head:pull/300

PR: https://git.openjdk.java.net/jmc/pull/300