avro

AVRO-2594: Use JAVA env when building local docker. (#709)

* AVRO-2594: Use JAVA env when building local docker.

* AVRO-2594: Move test command to build.sh.

* Add Dockerfile bash CMD for default.

* AVRO-2594: Add both JDKs to container.

* AVRO-2594: Set JAVA environment in Yetus docker.

* AVRO-2594: Clarify comment.

* Use portable form of bash functions.

* AVRO-2594: Update script documentation.

Make the script sourceable in bash to reuse the function.

* AVRO-2594: Document choice in Dockerfile.

* AVRO-2594: Fix sourcing from bash.

* AVRO-2594: Avoid build errors when java not installed.

* AVRO-2594: Don't change java version if target doesn't use java.