[8.x] backport all undertow related changes

As title says, backport all undertow subsystem changes from master
with exception of
- https://github.com/wildfly/wildfly/commit/880bc7d9e7b92fff94a20c7d334ab562f88b82c1
- https://github.com/wildfly/wildfly/commit/99c8e0e3084fbcd4880aa8342abcabbe0488c552
- https://github.com/wildfly/wildfly/commit/26b0c6cf254da7adbe913195e65abb2f02245a16

It also introduces undertow xsd schema version 1.2, which is atm the same as 2.0 in master. Will send PR for master shortly to sort this out.

Also this brings Undertow 1.1 and XNIO 3.3 to 8.x!