Java: Switch to `bach` for installing and managing JDKs

[BanzaiMan]

In travis-ci/travis-ci#9368, user @sormuras mentions bach, which aims to set up *JDK environments. This effectively replaces our webupd8-package-based Java cookbooks and jdk_switcher for switching Java runtimes.

See travis-ci/travis-ci#9368, travis-ci/travis-build#1347

Pros:

1. It is not dependent on a third-party packager, who seem to lag in supporting more recent JDK releases.

Cons:

1. It is a change.
2. May not play well with existing Java installations.

[sormuras]

For your consideration: https://github.com/shyiko/jabba also looks promising. Same pros and cons apply.

[jayvdb]

It looks like this is already active.

See https://travis-ci.community/t/install-jdk-sh-failing-for-openjdk9-and-10/ for some of the breakages it is causing.
Actually I have been seeing lots of different java breakages over the last few weeks, every few days one the java versions has been breaking, and I have been removing them from my matrix, but I dont have many left now.

[jayvdb]

It looks like all Oracle versions are going to be removed ? sormuras/bach#56 . I would have expected the new versions to not be added due to recent licensing changes, but old ones to remain. Looks like nobody kept a copy , or all online copies are being vanished .. :/

[jayvdb]

jabba integration scripts at https://github.com/DanySK/Gravis-CI ; thread https://travis-ci.community/t/gravis-ci-reliable-multiplatform-java-gradle-builds-on-travis-ci/4073