Add a linter rule for unary prefix expression spacing
Summary: Add a linter rule to ensure that there is no space between the operator and the operand in a unary prefix expression.
Test Plan: Added test cases.
Reviewers: epriestley, #blessed_reviewers
Reviewed By: epriestley, #blessed_reviewers
Subscribers: Korvin
Differential Revision: https://secure.phabricator.com/D13797