RFR: 8323601: Improve LayoutPath.PathElement::toString [v2]

[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 PathElement:toString

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17417/files
  - new: https://git.openjdk.org/jdk/pull/17417/files/a9c78ea8..83cf10c5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17417&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17417&range=00-01

  Stats: 25 lines in 3 files changed: 2 ins; 8 del; 15 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