Fix the file mode for the PHPCSFixer.

These changes were applied:
- Added the executable flag.

So that:
- The pretty print helper will actually detect this script.

TODO/FIXME:
- This component should allow us to optionally specify a cs fixer config
  from a common location within the repository.

Related Commit(s):
91b559f15cd50ff83572038227438db408743436