RFR: 8356888: (fs) FileSystems.newFileSystem that take an env must specify IllegalArgumentException

[Brian Burkhalter]

Add a throws clause for `IllegalArgumentException` to the `java.nio.file.FileSystems` methods `newFileSystem(Path, Map)` and `newFileSystem(Path, Map, ClassLoader)`. Also update the equivalent IAE verbiage for the analogous methods which accept a `URI` parameter instead of a `Path`.

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Commit messages:
 - 8356888: (fs) FileSystems.newFileSystem that take an env must specify IllegalArgumentException

Changes: https://git.openjdk.org/jdk/pull/25376/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25376&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8356888
  Stats: 15 lines in 1 file changed: 10 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/25376.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25376/head:pull/25376

PR: https://git.openjdk.org/jdk/pull/25376