[jdk13u-dev] RFR: 8226374: Restrict TLS signature schemes and named groups

[Olga Mikhaltsova]

Please review this backport of JDK-8226374 to jdk13u.
This patch is also required for clean backport of JDK-8233954 to jdk13u.

The patch didn't apply cleanly due to the context change in SignatureScheme.java by backport of JDK-8242141. 
A slight conflict was merged.

-------------

Commit messages:
 - Backport 316140ff92af7ac1aadb74de9cd37a5f3c412406

Changes: https://git.openjdk.java.net/jdk13u-dev/pull/20/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk13u-dev&pr=20&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8226374
  Stats: 1116 lines in 18 files changed: 497 ins; 313 del; 306 mod
  Patch: https://git.openjdk.java.net/jdk13u-dev/pull/20.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk13u-dev pull/20/head:pull/20

PR: https://git.openjdk.java.net/jdk13u-dev/pull/20