Bug: Measure Report period setting timezone offset

[Capt-Mac]

When running $evaluate-measure with default CQL measurement period or using periodStart & periodEnd parameters, the output Measure Report would persist an offset DateTime value for the period, which differs from input parameters.

Steps:

1. post a quality measure bundle to a fhir server, where the embedded cql contains a default DateTime measurement period [2020-01-01T00:00:00, 2020-12-31T12:59:59.9].
2. execute $evaluate-measure?periodStart=2020-01-01T00:00:00&periodEnd=2020-12-31T12:59:59.9 or leave parameters empty for measurementPeriod to rely on the default parameter values
3. the operation responds with a Measure Report resource where MeasureReport.period persists offset values.

Observed Results:

"period": {
        "start": "2020-01-01T00:00:00-07:00",
        "end": "2020-12-31T23:59:59-07:00"
    }

Expected Results:

"period": {
        "start": "2020-01-01T00:00:00",
        "end": "2020-12-31T23:59:59"
    }