RFR: 8166026: Refactor java/lang shell tests to java

[Ivan Šipka]

Refactor `test/jdk/java/lang/SecurityManager/modules/CustomSecurityManager.sh` as java test.

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Commit messages:
 - 8166026: Refactor java/lang shell tests to java

Changes: https://git.openjdk.java.net/jdk/pull/1579/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1579&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8166026
  Stats: 173 lines in 3 files changed: 73 ins; 100 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1579.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1579/head:pull/1579

PR: https://git.openjdk.java.net/jdk/pull/1579