[SPARK-14865][SQL] Better error handling for view creation.

## What changes were proposed in this pull request?
This patch improves error handling in view creation. CreateViewCommand itself will analyze the view SQL query first, and if it cannot successfully analyze it, throw an AnalysisException.

In addition, I also added the following two conservative guards for easier identification of Spark bugs:

1. If there is a bug and the generated view SQL cannot be analyzed, throw an exception at runtime. Note that this is not an AnalysisException because it is not caused by the user and more likely indicate a bug in Spark.
2. SQLBuilder when it gets an unresolved plan, it will also show the plan in the error message.

I also took the chance to simplify the internal implementation of CreateViewCommand, and *removed* a fallback path that would've masked an exception from before.

## How was this patch tested?
1. Added a unit test for the user facing error handling.
2. Manually introduced some bugs in Spark to test the internal defensive error handling.
3. Also added a test case to test nested views (not super relevant).

Author: Reynold Xin <rxin@databricks.com>

Closes #12633 from rxin/SPARK-14865.