RFR: 8323601: Improve LayoutPath.PathElement::toString [v4]

[Per Minborg]

> This PR proposes to add an improved Improve `LayoutPath.PathElement::toString` method simplifying debugging.
> 
> Opinions and suggestions for `static PathElement sequenceElement(long start, long step)` are welcome.

Per Minborg has updated the pull request incrementally with one additional commit since the last revision:

  Rework the LayoutPath::toString output

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17417/files
  - new: https://git.openjdk.org/jdk/pull/17417/files/269523b8..41c5a602

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17417&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17417&range=02-03

  Stats: 13 lines in 2 files changed: 0 ins; 0 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/17417.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17417/head:pull/17417

PR: https://git.openjdk.org/jdk/pull/17417