[AURON #1745] Introduce auron-spark-tests submodule for correctness testing

[xumingming]

Which issue does this PR close?

First PR for #1745 , establish the skeleton for correctness testing

Rationale for this change

N/A.

What changes are included in this PR?

We introduced submodule auron-spark-tests for correctness testing. It has submodules: common and spark33.

• common contains the helper classes for the whole correctness testing: setup the native engine enabled spark conf, enable/disable some test cases etc.
• spark33 is the submodule that contains test cases for Spark 3.3, in this PR we included one test suite: AuronStringFunctionsSuite for demo purpose.

Each sparkxx submodule contains a AuronSparkTestSettings which controls what test suites/test cases to enable/disable:

  enableSuite[AuronStringFunctionsSuite]
    // See https://github.com/apache/auron/issues/1724
    .exclude("string / binary substring function")

We actually do find a bug for substring function, so I disabled corresponding test here.

In different Spark version's module, we might have different enables/disables.

Are there any user-facing changes?

No.

How was this patch tested?

Added UTs.