FEC-14359: add param to override service URL (#256)

### Description of the Changes

Please add a detailed description of the change, whether it's an
enhancement or a bugfix.
If the PR is related to an open issue please link to it.

**Issue:**

**Fix:**

#### Resolves FEC-[Please add the ticket reference here]

docs/configuration.md

@@ -99,7 +99,8 @@ var provider = new playkit.providers.ott.Provider(config);
 >  serviceUrl: string,
 >  cdnUrl: string,
 >  useApiCaptions: boolean,
->  replaceHostOnlyManifestUrls: boolean // optional
+>  replaceHostOnlyManifestUrls: boolean, // optional
+>  overrideServiceUrl: string //optional
 > }
 > ```
 >
@@ -112,7 +113,8 @@ var provider = new playkit.providers.ott.Provider(config);
 >  serviceUrl: "//www.kaltura.com/api_v3",
 >  cdnUrl: "//cdnapisec.kaltura.com",
 >  useApiCaptions: true,
->  replaceHostOnlyManifestUrls: false
+>  replaceHostOnlyManifestUrls: false,
+>  overrideServiceUrl : null
 > }
 > ```
 >

src/k-provider/ovp/config.ts

@@ -15,6 +15,9 @@ const defaultConfig: any = {
 
 export default class OVPConfiguration {
   public static set(clientConfig?: ProviderEnvConfigObject): void {
+    if(clientConfig?.overrideServiceUrl) {
+      clientConfig.serviceUrl = clientConfig.overrideServiceUrl;
+    }
     if (clientConfig) {
       Object.assign(defaultConfig, clientConfig);
     }

src/types/env-config.ts

@@ -4,4 +4,5 @@ export type ProviderEnvConfigObject = {
   analyticsServiceUrl?: string;
   useApiCaptions?: boolean;
   replaceHostOnlyManifestUrls?: boolean;
+  overrideServiceUrl?: string;
 };