RFR: 8297687: new URI(S, S, S, S) throws exception with incorrect index position reported in the error message

[Daniel Fuchs]

In some circumstance, when using a constructor that expects a hostname and the hostname contains an illegal character, the URISyntaxException which is thrown might contain a misleading index pointing at the start of the authority component, instead of pointing at the illegal character that was found.

This change fixes the misreported index, and adds corresponding tests to the URI/Test.java infrastructure.

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Commit messages:
 - 8297687

Changes: https://git.openjdk.org/jdk/pull/11518/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11518&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8297687
  Stats: 51 lines in 2 files changed: 48 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/11518.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11518/head:pull/11518

PR: https://git.openjdk.org/jdk/pull/11518