Adding the missing export for KeyCredential in ts http runtime lib (Azure#27631)

Adding the missing export for KeyCredential for ts http runtime lib

Author: MaryGao

sdk/core/ts-http-runtime/review/ts-http-runtime.api.md

@@ -41,7 +41,6 @@ export function addCredentialPipelinePolicy(pipeline: Pipeline, baseUrl: string,
 // @public
 export interface AddCredentialPipelinePolicyOptions {
     clientOptions?: ClientOptions;
-    // Warning: (ae-forgotten-export) The symbol "KeyCredential" needs to be exported by the entry point index.d.ts
     credential?: TokenCredential | KeyCredential;
 }
 
@@ -363,6 +362,11 @@ export function isRestError(e: unknown): e is RestError;
 // @public
 export const isWebWorker: boolean;
 
+// @public
+export interface KeyCredential {
+    readonly key: string;
+}
+
 // @public
 export interface KeyObject {
     passphrase?: string | undefined;

sdk/core/ts-http-runtime/src/index.ts

@@ -69,6 +69,7 @@ export {
 export { AbortSignalLike } from "./abort-controller/AbortSignalLike";
 export { AbortError } from "./abort-controller/AbortError";
 export { AccessToken, GetTokenOptions, TokenCredential } from "./auth/tokenCredential";
+export { KeyCredential } from "./auth/keyCredential";
 export {
   Instrumenter,
   InstrumenterSpanOptions,