RFR: 8253761: Fix URI syntax of jar --describe-module

[Christian Stein]

This commit replaces `"/!"` with `"!/"` in order to generate
valid URIs when printing a module description of a modular
JAR file. A valid URI is described here: [1]

https://bugs.openjdk.java.net/browse/JDK-8253761

[1] https://docs.oracle.com/en/java/javase/15/docs/api/java.base/java/net/JarURLConnection.html

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Commit messages:
 - 8253761: Fix URI syntax of jar --describe-module

Changes: https://git.openjdk.java.net/jdk/pull/393/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=393&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8253761
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/393.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/393/head:pull/393

PR: https://git.openjdk.java.net/jdk/pull/393