fix(change_detector): Fix for detecting NanN moves in collections

[vicb]

Closes #1136

[vicb]

Some details about this PR:

• Factorize loose identity in _looseIdentical() -> identical which also support NaN and String test by value - the code was used at a few different places and should have been used at even more places.
• Add support for detecting NaN moves (bug fix)
  • DuplicateMap now support NaN (it would raise an assertion error before)
  • DuplicateMap no longer test with identical but uses _looseIdentical
• Improve performance (marginally): before this change we would check for re-insertion when value are not indentical(), now we only check after values are not _looseIdentical(). The perf impact occurs only where we have two Strings that are == but not identical or two NaN at the same index.