add probability service

libs/nshmp-haz/www/probability-service/index.ts

+export * from './probability-response.model';
+export * from './probability-usage.model';

libs/nshmp-haz/www/probability-service/probability-response.model.ts

+import {Response} from '../../../nshmp-ws-utils';
+import {RateRequestData, RateResponseData} from '../rates-service';
+
+export type ProbabilityResponse = Response<
+  ProbabilityRequestData,
+  RateResponseData
+>;
+
+export interface ProbabilityRequestData extends RateRequestData {
+  timespan: number;
+}

libs/nshmp-haz/www/probability-service/probability-usage.model.ts

+import {Response} from '../../../nshmp-ws-utils';
+import {DoubleParameter} from '../../../nshmp-ws-utils/metadata';
+import {RateRequestMetadata} from '../rates-service/rate-usage.model';
+
+export type ProbabilityUsage = Response<string, ProbabilityRequestMetadata>;
+
+export interface ProbabilityRequestMetadata extends RateRequestMetadata {
+  timespane: DoubleParameter;
+}