[SPARK-9690][ML][PYTHON] pyspark CrossValidator random seed

[jkbradley]

Extend CrossValidator with HasSeed in PySpark.

This PR replaces [https://github.com//pull/7997]

CC: @yanboliang @thunterdb @mmenestret Would one of you mind taking a look? Thanks!

[SparkQA]

Test build #47591 has finished for PR 10268 at commit 85aae68.

• This patch fails PySpark unit tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):\n * class CrossValidator(Estimator, HasSeed):\n

[SparkQA]

Test build #2210 has finished for PR 10268 at commit 2f60607.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):\n * class CrossValidator(Estimator, HasSeed):\n * class ExecutorClassLoader(\n

[yanboliang]

Add \ at the end of line, otherwise it can not generate python doc correctly.

[yanboliang]

LGTM except minor issues.

[jkbradley]

@yanboliang Thanks! With the fix, it worked when I generated the docs locally.

[SparkQA]

Test build #47766 has finished for PR 10268 at commit 0bd1457.

• This patch fails RAT tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):\n * class CrossValidator(Estimator, HasSeed):\n

[SparkQA]

Test build #2219 has finished for PR 10268 at commit 0bd1457.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):\n * class CrossValidator(Estimator, HasSeed):\n

[yanboliang]

We set default value of seed to this.getClass.getName.hashCode.toLong at Scala side. I think we should keep consistent with that, otherwise users may get different result when training with the same dataset.

[jkbradley]

This is just an example though. But I agree we could remove the seed now to simplify the example. I'll do that.

[yanboliang]

@jkbradley I think it's the last issue that we should resolve, thanks!

[SparkQA]

Test build #47844 has finished for PR 10268 at commit 9bf75ad.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):\n * class CrossValidator(Estimator, HasSeed):\n

[jkbradley]

Merged with master