RFR: 8288897: Clean up node dump code [v4]

[Emanuel Peter]

> I recently did some work in the area of `Node::dump` and `Node::find`, see [JDK-8287647](https://bugs.openjdk.org/browse/JDK-8287647) and [JDK-8283775](https://bugs.openjdk.org/browse/JDK-8283775).
> 
> This change sets cleans up the code around, and tries to reduce code duplication.
> 
> Things I did:
> - remove Node::related. It was added 7 years ago, with [JDK-8004073](https://bugs.openjdk.org/browse/JDK-8004073). However, it was not extended to many nodes, and hence it is incomplete, and nobody I know seems to use it.
> - refactor `dump(int)` to use `dump_bfs` (reduce code duplication).
> - redefine categories in `dump_bfs`, focusing on output types. Mixed type is now also control if it has control output, and memory if it has memory output, etc. Plus, a node is also in the control category if it `is_CFG`. This makes `dump_bfs` much more usable, to traverse control and memory flow.
> - Other small cleanups, like replacing rarely used dump functions with dump, making removing dead code, make some functions private
> - Adding `call from debugger` comment to VM functions that are useful in debugger

Emanuel Peter has updated the pull request incrementally with one additional commit since the last revision:

  implementing Christians review suggestions

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/9234/files
  - new: https://git.openjdk.org/jdk/pull/9234/files/b2a2f58f..a95b1260

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9234&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9234&range=02-03

  Stats: 45 lines in 1 file changed: 10 ins; 22 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/9234.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9234/head:pull/9234

PR: https://git.openjdk.org/jdk/pull/9234