RFR: 8278595: Provide more information when a pipeline can't be used [v3]

[Johan Vos]

> This PR provides at least some basic information when a pipeline can't be used. 
> There are a number of reasons why a candidate pipeline can't be used, and this PR makes it clear at which point the pipeline fails. 
> 
> The changes are only applied in case `prism.verbose` is already set to `true`, so there is no unwanted logging.

Johan Vos has updated the pull request incrementally with one additional commit since the last revision:

  fix one more whitespace issue

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Changes:
  - all: https://git.openjdk.java.net/jfx/pull/693/files
  - new: https://git.openjdk.java.net/jfx/pull/693/files/fe0efa74..c779418b

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=693&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=693&range=01-02

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/693.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/693/head:pull/693

PR: https://git.openjdk.java.net/jfx/pull/693