sql: support new sql to show the distribution for the given table

[bufferflies]

Feature Request

TiDB has provided the sql to show the location of every region. But sometimes users want to detect the hotspot in stores distinct by tikv/tiflash instance.

Is your feature request related to a problem? Please describe:
The DBA can use more complex SQL to show the distribution of every instance such as grouping by the table TIKV_REGION_PEERS and join in TIKV_REGION_STATUS.

Describe the feature you'd like:

TIDB can provide another SQL to show the distribution of special instances, such as:

show table t1 distribution;

+---------+------------+----------------+----------+------------+-------------------+--------------------+-----------------+------------------+
| DB_NAME | TABLE_NAME | PARTITION_NAME | STORE_ID | STORE_TYPE | REGION_LEADER_NUM | REGION_LEADER_BYTE | REGION_PEER_NUM | REGION_PEER_BYTE |
+---------+------------+----------------+----------+------------+-------------------+--------------------+-----------------+------------------+
| db_1    | table_foo  |                | 1        | TiKV       |               315 |        24057934521 |            1087 |      86938746542 |
| db_1    | table_foo  |                | 2        | TiKV       |               324 |        28204839240 |            1104 |      91039476832 |
| db_1    | table_foo  |                | 3        | TiKV       |               319 |        25986274812 |            1091 |      89405367423 |
| db_1    | table_foo  |                | 4        | TiKV       |               503 |        41039587625 |            1101 |      90482317797 |
+---------+------------+----------------+----------+------------+-------------------+--------------------+-----------------+------------------+

Describe alternatives you've considered:

Teachability, Documentation, Adoption, Migration Strategy: