[SPARK-20703][SQL] Associate metrics with data writes onto DataFrameWriter operations

## What changes were proposed in this pull request?

Right now in the UI, after SPARK-20213, we can show the operations to write data out. However, there is no way to associate metrics with data writes. We should show relative metrics on the operations.

#### Supported commands

This change supports updating metrics for file-based data writing operations, including `InsertIntoHadoopFsRelationCommand`, `InsertIntoHiveTable`.

Supported metrics:

* number of written files
* number of dynamic partitions
* total bytes of written data
* total number of output rows
* average writing data out time (ms)
* (TODO) min/med/max number of output rows per file/partition
* (TODO) min/med/max bytes of written data per file/partition

####  Commands not supported

`InsertIntoDataSourceCommand`, `SaveIntoDataSourceCommand`:

The two commands uses DataSource APIs to write data out, i.e., the logic of writing data out is delegated to the DataSource implementations, such as  `InsertableRelation.insert` and `CreatableRelationProvider.createRelation`. So we can't obtain metrics from delegated methods for now.

`CreateHiveTableAsSelectCommand`, `CreateDataSourceTableAsSelectCommand` :

The two commands invokes other commands to write data out. The invoked commands can even write to non file-based data source. We leave them as future TODO.

#### How to update metrics of writing files out

A `RunnableCommand` which wants to update metrics, needs to override its `metrics` and provide the metrics data structure to `ExecutedCommandExec`.

The metrics are prepared during the execution of `FileFormatWriter`. The callback function passed to `FileFormatWriter` will accept the metrics and update accordingly.

There is a metrics updating function in `RunnableCommand`. In runtime, the function will be bound to the spark context and `metrics` of `ExecutedCommandExec` and pass to `FileFormatWriter`.

## How was this patch tested?

Updated unit tests.

Author: Liang-Chi Hsieh <viirya@gmail.com>

Closes #18159 from viirya/SPARK-20703-2.