migrate xcompat tests to use new test vector framework

[mattsb42-aws]

The xcompat tests[1] currently use the legacy test vectors[2]. We need to update them to use the new test vector framework[3] and the corresponding test vectors[4].

[1] https://github.com/aws/aws-encryption-sdk-java/blob/master/src/test/java/com/amazonaws/encryptionsdk/XCompatDecryptTest.java
[2] https://github.com/awslabs/aws-encryption-sdk-test-vectors/tree/master/vectors/awses-legacy
[3] https://github.com/awslabs/aws-crypto-tools-test-vector-framework
[4] https://github.com/awslabs/aws-encryption-sdk-test-vectors/tree/master/vectors/awses-decrypt

[SalusaSecondus]

No longer needed as TestVectorRunner from #127 uses the new framework.