AzureBlobFSFile Missing modifiedDatetimeStart and modifiedDatetimeEnd

Hi @FancyGecko Python SDK is generated with swagger automatically. Related swagger is [here](https://github.com/Azure/azure-rest-api-specs/blob/main/specification/datafactory/resource-manager/Microsoft.DataFactory/stable/2018-06-01/entityTypes/Dataset.json#L1446-L1468) and we do not have property `modifiedDatetimeStart` and `modifiedDatetimeEnd` for type `AzureBlobFSFile`. Please open issue in https://github.com/Azure/azure-rest-api-specs/issues and mark with label feature request. Once swagger is fixed, python SDK will release new version to support it.

_Originally posted by @ChenxiJiang333 in https://github.com/Azure/azure-sdk-for-python/issues/32959#issuecomment-1801158820_

Start with specification/datafactory/resource-manager/Microsoft.DataFactory/stable/2018-06-01/entityTypes/Dataset.json at lines 1446-1468 and inspect the AzureBlobFSFile definition. Confirm how the related datetime properties are represented for comparable types, then update the specification so both properties are defined for AzureBlobFSFile and validate the specification if repository guidance provides a check.

Written by the indexing model from the issue text.