RFR: 8271356: Modify jdb to treat an empty command as a repeat of the previous command [v3]

[Jakob Cornell]

> This has been under discussion on and off for the past month or so on serviceability-dev, and I think a CSR request is required, so this may be a work in progress.
> 
> Notes on the patch:
> 
> - The `list` command previously marked a line in each listing with `=>`.  In a bare `list` this is the next line up for execution.  Previously when requesting a specific location (e.g. `list 5`) the requested line would be marked.  With the patch applied, `list` will only ever mark the next line up for execution.  This is consistent with the behavior of GDB and PDB (at least).
> - `EOF` is printed when the repeat setting is on and a bare `list` command follows a listing containing the last source line.  This feature is from PDB; it's a somewhat softer message than the one for an explicit `list` request that's out of range.
> - I don't speak Chinese or Japanese, so I've omitted localizations for the new messages in those locales.  However, I updated the help text in both to include the new commands, with the descriptions left empty for now.

Jakob Cornell has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:

  8271356: JDB: implement GDB-style command repetition and `list' auto-advance

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5290/files
  - new: https://git.openjdk.java.net/jdk/pull/5290/files/6328744f..a44b8b4b

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5290&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5290&range=01-02

  Stats: 206 lines in 1 file changed: 15 ins; 18 del; 173 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5290.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5290/head:pull/5290

PR: https://git.openjdk.java.net/jdk/pull/5290