[Tests] Adds a test suite for `EMAModel` (#2530)
* ema test cases.
* debugging maessages.
* debugging maessages.
* add: tests for ema.
* fix: optimization_step arg,
* handle device placement.
* Apply suggestions from code review
Co-authored-by: Will Berman <wlbberman@gmail.com>
* remove del and gc.
* address PR feedback.
* add: tests for serialization.
* fix: typos.
* skip_mps to serialization.
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Co-authored-by: Will Berman <wlbberman@gmail.com>
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>
