[TRIVIAL][SQL] Match the name of OrcRelation companion object to OrcFileFormat

[HyukjinKwon]

What changes were proposed in this pull request?

This PR simply matches the name OrcRelation to OrcFileFormat.

Just to make sure, ParquetFileFormat has the object named ParquetFileFormat and the related ones were renamed in 361ebc2 all together but it seems renamingOrcFileFormat was missed.

How was this patch tested?

N/A

[HyukjinKwon]

BTW, CSVRelation also exists in a separate file but #13988 includes this change.

[SparkQA]

Test build #63334 has finished for PR 14529 at commit d7b81ba.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #67390 has finished for PR 14529 at commit bca3be8.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[rxin]

OK I will include this in my next pr.

[HyukjinKwon]

Thanks, I am closing this!