[SPARK-19329][SQL] Reading from or writing to a datasource table with a non...

[SPARK-19329][SQL] Reading from or writing to a datasource table with a non pre-existing location should succeed

## What changes were proposed in this pull request?

when we insert data into a datasource table use `sqlText`, and the table has an not exists location,
this will throw an Exception.

example:

```
spark.sql("create table t(a string, b int) using parquet")
spark.sql("alter table t set location '/xx'")
spark.sql("insert into table t select 'c', 1")
```

Exception:
```
com.google.common.util.concurrent.UncheckedExecutionException: org.apache.spark.sql.AnalysisException: Path does not exist: /xx;
at com.google.common.cache.LocalCache$LocalLoadingCache.getUnchecked(LocalCache.java:4814)
at com.google.common.cache.LocalCache$LocalLoadingCache.apply(LocalCache.java:4830)
at org.apache.spark.sql.hive.HiveMetastoreCatalog.lookupRelation(HiveMetastoreCatalog.scala:122)
at org.apache.spark.sql.hive.HiveSessionCatalog.lookupRelation(HiveSessionCatalog.scala:69)
at org.apache.spark.sql.catalyst.analysis.Analyzer$ResolveRelations$.org$apache$spark$sql$catalyst$analysis$Analyzer$ResolveRelations$$lookupTableFromCatalog(Analyzer.scala:456)
at org.apache.spark.sql.catalyst.analysis.Analyzer$ResolveRelations$$anonfun$apply$8.applyOrElse(Analyzer.scala:465)
at org.apache.spark.sql.catalyst.analysis.Analyzer$ResolveRelations$$anonfun$apply$8.applyOrElse(Analyzer.scala:463)
at org.apache.spark.sql.catalyst.plans.logical.LogicalPlan$$anonfun$resolveOperators$1.apply(LogicalPlan.scala:61)
at org.apache.spark.sql.catalyst.plans.logical.LogicalPlan$$anonfun$resolveOperators$1.apply(LogicalPlan.scala:61)
at org.apache.spark.sql.catalyst.trees.CurrentOrigin$.withOrigin(TreeNode.scala:70)
at org.apache.spark.sql.catalyst.plans.logical.LogicalPlan.resolveOperators(LogicalPlan.scala:60)
at org.apache.spark.sql.catalyst.analysis.Analyzer$ResolveRelations$.apply(Analyzer.scala:463)
at org.apache.spark.sql.catalyst.analysis.Analyzer$ResolveRelations$.apply(Analyzer.scala:453)
```

As discussed following comments, we should unify the action when we reading from or writing to a datasource table with a non pre-existing locaiton:

1. reading from a datasource table: return 0 rows
2. writing to a datasource table:  write data successfully

## How was this patch tested?
unit test added

Author: windpiger <songjun@outlook.com>

Closes #16672 from windpiger/insertNotExistLocation.