RFR: 8344336: SM cleanup of java.lang.System, Runtime, String, StackWalker

[Roger Riggs]

Removed use of SecurityManager to check permissions.
Relaxed defensive copying of byte arrays (due to lack of SM)

Refresh of PR#22168 Including review comments made there.

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Commit messages:
 - Refactor package private method `codeSource` into Module where it is used.
 - Review suggestions applied:
 - 8344336: SM cleanup of java.lang.System, Runtime, String, StackWalker

Changes: https://git.openjdk.org/jdk/pull/22282/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22282&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8344336
  Stats: 208 lines in 6 files changed: 5 ins; 194 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/22282.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22282/head:pull/22282

PR: https://git.openjdk.org/jdk/pull/22282