[jdk11u-dev] RFR: 8284047: Harmonize/Standardize the SSLSocket/SSLEngine/SSLSocketSSLEngine test templates

[Antonio Vieiro]

Backport of [JDK-8284047](https://bugs.openjdk.org/browse/JDK-8284047) from 17 to 11, to improve different templates for SSL tests. This builds on top of #3150 , and will be followed up by backports of JDK-8306014 and JDK-8306015. The changes converts `SSLContextTemplate` into an abstract class from an interface, and moves different methods and constants from `SSLSocketTemplate` into this new base class. It also drops the `SSLSocketSSLEngine` template.

The backport is not clean, because JDK11 is still using legacy elliptic curves that were removed in JDK16 via [JDK-8252601](https://bugs.openjdk.org/browse/JDK-8252601) but are not in 11. As a consequence the `CA_ECDSA_SECT283R1` and `EE_ECDSA_SECT283R1` are not present in the JDK17 commit, but must still be retained in JDK11.

Similarlly, `DisabledCurves.java` must still use the `**SECT_283R1` certificates, and not the `**SECP384R1` onesas in 17, since [JDK-8252601](https://bugs.openjdk.org/browse/JDK-8252601) is not in 11.

Security tests continue to pass:


==============================
Test summary
==============================
   TEST                                              TOTAL  PASS  FAIL ERROR   
   jtreg:test/jdk:jdk_security                        1361  1361     0     0   
==============================
TEST SUCCESS

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Depends on: https://git.openjdk.org/jdk11u-dev/pull/3150

Commit messages:
 - Backport 5e0be4886b2923309a820d2d6230d9071430ebc7

Changes: https://git.openjdk.org/jdk11u-dev/pull/3151/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=3151&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8284047
  Stats: 4425 lines in 23 files changed: 1059 ins; 3039 del; 327 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/3151.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/3151/head:pull/3151

PR: https://git.openjdk.org/jdk11u-dev/pull/3151