[SPARK-14135] Add off-heap storage memory bookkeeping support to MemoryManager

[JoshRosen]

This patch extends Spark's UnifiedMemoryManager to add bookkeeping support for off-heap storage memory, an requirement for enabling off-heap caching (which will be done by #11805). The MemoryManager's storageMemoryPool has been split into separate on- and off-heap pools and the storage and unroll memory allocation methods have been updated to accept a memoryMode parameter to specify whether allocations should be performed on- or off-heap.

In order to reduce the testing surface, the StaticMemoryManager does not support off-heap caching (we plan to eventually remove the StaticMemoryManager, so this isn't a significant limitation).

[SparkQA]

Test build #54074 has finished for PR 11942 at commit 69e22fe.

• This patch fails Scala style tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #54077 has finished for PR 11942 at commit c4d2aeb.

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

[JoshRosen]

Jenkins, retest this please.

[SparkQA]

Test build #54080 has finished for PR 11942 at commit c4d2aeb.

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

[SparkQA]

Test build #54196 has finished for PR 11942 at commit 61d220b.

• This patch fails to build.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #54201 has finished for PR 11942 at commit c3d0f61.

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

[JoshRosen]

Jenkins, retest this please.

[JoshRosen]

Jenkins, retest this please.

[SparkQA]

Test build #54204 has finished for PR 11942 at commit c3d0f61.

• This patch fails from timeout after a configured wait of 250m.
• This patch merges cleanly.
• This patch adds no public classes.

[JoshRosen]

/cc @andrewor14@nongli@rxin, could one of you review this to unblock the off-heap patch?

[SparkQA]

Test build #54223 has finished for PR 11942 at commit c3d0f61.

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

[davies]

LGTM

[SparkQA]

Test build #2698 has finished for PR 11942 at commit c3d0f61.

• This patch passes all tests.
• This patch does not merge cleanly.
• This patch adds no public classes.

[rxin]

Merging in master. Thanks.