Use more strict shema for ReportFilter's segmentDefinition

[mems]

The field segmentDefinition of ReportFilter should use the AnalyticsSegmentDefinition schema instead of object:

analytics-2.0-apis/docs/swagger.json

Lines 5310 to 5315 in 00dfe28

	"segmentDefinition": {
	"type": "object",
	"additionalProperties": {
	"type": "object"
	}
	},

[gigazelle]

Looks like this is complete - thank you for the PR!