Strip whitespace in disallow_raw_sql!

[gmcgibbon]

Summary

Closes #41307

Support proper SQL parsing for multiple column strings in pluck.

Before:

User.pluck("first_name, last_name") #=> SELECT first_name, last_name FROM "users"
User.pluck("first_name, last_name\n") #=> ActiveRecord::UnknownAttributeReference

After:

User.pluck("first_name, last_name") #=> SELECT first_name, last_name FROM "users"
User.pluck("first_name, last_name\n") #=> SELECT first_name, last_name\n FROM "users"

Simply strips whitespace from the SQL sanitization checks of pluck.

[kaspth]

I'd vote for deprecating, since pluck("first_name, last_name") won't fit with the Enumerable version of pluck.

[gmcgibbon]

Hm, this also seems to conflict with invoking SQL functions in pluck. I'll go ahead and try to deprecate instead.

[rafaelfranca]

pluck(Arel.sql("some_sql_transformation(first_name)")) should still be supported. So I don't think not matching Enumerator version of pluck is enough reason to deprecate that.

[gmcgibbon]

Given I can't deprecate string / comma delimited strings, I've decided to simply use strip in the SQL sanitizing method (like the issue originally suggested). Parsing SQL into an AST isn't worth it with all the edge cases and potential speed regressions.