TypeScript timestamp input serialization should not remove milliseconds

[rkyker]

As per the Smithy documentation 6.4. timestampFormat trait:

• date-time: "...with optional millisecond precision..."
• epoch-seconds: "...with optional millisecond precision (for example, 1515531081.123). Values that are more granular than millisecond precision SHOULD be truncated to fit millisecond precision. "

Currently in: HttpProtocolGeneratorUtils - getTimestampInputParam()

• The milliseconds are removed from the output DATA_TIME format
• The milliseconds are rounded up to the second for the EPOCH_SECONDS format

In both cases the milliseconds (if present) should be passed through so that the input timestamp value is not modified by the serialization.

In particular, we are using the date-time format and need the milliseconds passed through.