[jdk11u-dev] RFR: 8302017: Allocate BadPaddingException only if it will be thrown

[Alexey Bakhtin]

Almost clean backport from [JDK17 PR](https://github.com/openjdk/jdk17u-dev/pull/1864)
The only difference is the copyright years and switch statement in the RSAPadding::unpad()

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Commit messages:
 - Backport 334b977259930368160db705c1f2feda0b0e8707

Changes: https://git.openjdk.org/jdk11u-dev/pull/2383/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2383&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8302017
  Stats: 155 lines in 5 files changed: 92 ins; 17 del; 46 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2383.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2383/head:pull/2383

PR: https://git.openjdk.org/jdk11u-dev/pull/2383