[SPARK-20023][SQL] Output table comment for DESC FORMATTED

### What changes were proposed in this pull request?
Currently, `DESC FORMATTED` did not output the table comment, unlike what `DESC EXTENDED` does. This PR is to fix it.

Also correct the following displayed names in `DESC FORMATTED`, for being consistent with `DESC EXTENDED`
- `"Create Time:"` -> `"Created:"`
- `"Last Access Time:"` -> `"Last Access:"`

### How was this patch tested?
Added test cases in `describe.sql`

Author: Xiao Li <gatorsmile@gmail.com>

Closes #17381 from gatorsmile/descFormattedTableComment.