[SPARK-23092][SQL] Migrate MemoryStream to DataSourceV2 APIs

[brkyvz]

What changes were proposed in this pull request?

This PR migrates the MemoryStream to DataSourceV2 APIs.

How was this patch tested?

All existing unit tests in streaming.

[SparkQA]

Test build #86192 has finished for PR 20279 at commit 7a0b564.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
• class OneHotEncoderEstimator(JavaEstimator, HasInputCols, HasOutputCols, HasHandleInvalid,
• class OneHotEncoderModel(JavaModel, JavaMLReadable, JavaMLWritable):
• class HasOutputCols(Params):
• class DataSourceRDDPartition[T : ClassTag](val index: Int, val readTask: ReadTask[T])
• class DataSourceRDD[T: ClassTag](

[SparkQA]

Test build #86190 has finished for PR 20279 at commit 50a541b.

• This patch fails Spark unit tests.
• This patch does not merge cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #86206 has finished for PR 20279 at commit a81c2ec.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[brkyvz]

Closed in favor of #20445

[SparkQA]

Test build #86854 has finished for PR 20279 at commit a81c2ec.

• This patch fails Spark unit tests.
• This patch does not merge cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #86853 has finished for PR 20279 at commit 9f6c6b9.

• This patch fails Spark unit tests.
• This patch does not merge cleanly.
• This patch adds no public classes.