perf($parse): removing binaryFn and valueFn wrappers from filter expressions

Improves parsed-expressions/filters benchmark by 15%.
refactor($parse): clean up object literal fn

No measurable impact on performance
refactor($parse): remove commented out code
fix($parse): ensure CSP assignable expressions have `assign()`

Fixes regression where the `assign()` method was not added to chains of identifiers in CSP mode,
introduced originally in b3b476d.

Also fixes the $parse test suite to ensure that CSP code paths are taken when they're expected to be
taken.

Closes #9048