[8u] TLSv1.3 RFR: 8245467: Remove 8u TLSv1.2 implementation files

[Alexey Bakhtin]

Please review changes required to backport TLSv1.3 protocol from JDK11.0.7 to JDK8u

This is the first part of backport discussed in the thread [1]

JBS task: https://bugs.openjdk.java.net/browse/JDK-8245467
Webrev: http://cr.openjdk.java.net/~abakhtin/tls1.3/8245466/8245467/webrev.v0/

This patch remove 8u TLSv1.2 implementation files and fixes issues discussed in [2] and [3]

[1] - https://mail.openjdk.java.net/pipermail/jdk8u-dev/2020-May/011664.html
[2] - https://mail.openjdk.java.net/pipermail/jdk8u-dev/2020-May/011735.html
[3] -
https://mail.openjdk.java.net/pipermail/jdk8u-dev/2020-May/011717.html

Regards
Alexey