Java: Add option to run IT on remote ports.

[Yury-Fridlyand]

Implementing #1375 to java client

To run IT:

./gradlew :integTest:test

To run IT on existing servers, add this to command line (update ports according to your setup):

-Dcluster-endpoints=localhost:7000 -Dstandalone-endpoints=localhost:6379

Additional parameter to enable TLS

-Dtls=true

To filter IT and run all tests from a specific class, add this to the command line:

--tests <classname>

To filter IT and run a very specific test, add this to the command line:

--tests '*.<test_name>'

⚠️ use quotes

Also this PR allows to use a remote-hosted server for testing.

[jonathanl-bq]

Looks fine to me, but honestly, someone else should probably read through the build.gradle changes.