Use CaseInsensitiveArray in ArcanistFunctionCallShouldBeTypeCastXHPASTLinterRule
Summary: Demonstrates the use of CaseInsensitiveArray. Depends on D14624.
Test Plan: Ran unit tests.
Reviewers: epriestley, #blessed_reviewers
Reviewed By: epriestley, #blessed_reviewers
Subscribers: Korvin
Differential Revision: https://secure.phabricator.com/D14625