[SPARK-17510][STREAMING][KAFKA] config max rate on a per-partition basis

## What changes were proposed in this pull request?

Allow configuration of max rate on a per-topicpartition basis.
## How was this patch tested?

Unit tests.

The reporter (Jeff Nadler) said he could test on his workload, so let's wait on that report.

Author: cody koeninger <cody@koeninger.org>

Closes #15132 from koeninger/SPARK-17510.

(cherry picked from commit 89d1fa58)
Signed-off-by: Shixiong Zhu <shixiong@databricks.com>