[SPARK-8820][Streaming] Add a configuration to set checkpoint dir.

[SaintBacchus]

Add a configuration to set checkpoint directory for convenience to user.
Jira Address

[SparkQA]

Test build #36521 has finished for PR 7218 at commit dd0acc1.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • case class ShiftRightUnsigned(left: Expression, right: Expression) extends BinaryExpression

[srowen]

I understand the motivation, but I would oppose adding yet more config and API surface area unless there's a clear need. I don't see that this does much.

[SaintBacchus]

adding yet more config and API surface area unless there's a clear need

@srowen Do you mean it's not necessary to add this config?
I purpose the user may not hard code the checkpoint directory or they must implement the config themself.

[andrewor14]

@tdas

[SaintBacchus]

@harishreedharan Can you also review this PR plz

[tdas]

Please added unit tests in StreamingContextSuite

[SparkQA]

Test build #37224 has finished for PR 7218 at commit 66ea47c.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[tdas]

Can you rename this configuration to spark.streaming.checkpoint.directory. This is to maintain cleanliness in the future if we add more configuration related to checkpointing (spark.streaming.checkpoint.*)

[harishreedharan]

LGTM

[SparkQA]

Test build #37295 has finished for PR 7218 at commit d49fe4b.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.