[SPARK-13681][SPARK-14458][SPARK-14566][SQL] Add back once removed...

[SPARK-13681][SPARK-14458][SPARK-14566][SQL] Add back once removed CommitFailureTestRelationSuite and SimpleTextHadoopFsRelationSuite

## What changes were proposed in this pull request?

These test suites were removed while refactoring `HadoopFsRelation` related API. This PR brings them back.

This PR also fixes two regressions:

- SPARK-14458, which causes runtime error when saving partitioned tables using `FileFormat` data sources that are not able to infer their own schemata. This bug wasn't detected by any built-in data sources because all of them happen to have schema inference feature.

- SPARK-14566, which happens to be covered by SPARK-14458 and causes wrong query result or runtime error when
  - appending a Dataset `ds` to a persisted partitioned data source relation `t`, and
  - partition columns in `ds` don't all appear after data columns

## How was this patch tested?

`CommitFailureTestRelationSuite` uses a testing relation that always fails when committing write tasks to test write job cleanup.

`SimpleTextHadoopFsRelationSuite` uses a testing relation to test general `HadoopFsRelation` and `FileFormat` interfaces.

The two regressions are both covered by existing test cases.

Author: Cheng Lian <lian@databricks.com>

Closes #12179 from liancheng/spark-13681-commit-failure-test.