RFR: 8267123: Remove RMI Activation

[Stuart Marks]

This is the implementation of [JEP 407](https://openjdk.java.net/jeps/407).

This is a fairly straightforward removal of this component.
 - Activation implementation classes removed
 - Activation tests removed
 - adjustments to various comments to remove references to Activation
 - adjustments to some code to remove special-case support for Activation from core RMI
 - adjustments to several tests to remove testing and support for, and mentions of Activation
 - remove `rmid` tool

(Personally, I found that reviewing using the webrev was easier than navigating github's diff viewer.)

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Commit messages:
 - Merge branch 'master' into JDK-8267123-Remove-RMI-Activation
 - Merge branch 'master' into remove-rmi-activation
 - Clean up some old comments.
 - Small fixups.
 - First cut at removal of RMI Activation.

Changes: https://git.openjdk.java.net/jdk/pull/4194/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4194&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8267123
  Stats: 21982 lines in 243 files changed: 0 ins; 21930 del; 52 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4194.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4194/head:pull/4194

PR: https://git.openjdk.java.net/jdk/pull/4194