Allow any provider into API constructor (#444)

* Allow any provider into API constructor

* Update documentation

* Remove combineLatest exposure (deprecation error)

* Linting & test cleanups

* Exclude docs from codeclimate

packages/rpc-provider/src/http/index.ts

@@ -49,6 +49,13 @@ export default class HttpProvider implements ProviderInterface {
     this.endpoint = endpoint;
   }
 
+  /**
+   * @summary `true` when this provider supports subscriptions
+   */
+  get hasSubscriptions (): boolean {
+    return false;
+  }
+
   /**
    * @summary Whether the node is connected or not.
    * @return {boolean} true if connected

packages/rpc-provider/src/mock/index.ts

@@ -67,6 +67,10 @@ export default class Mock implements ProviderInterface {
     this.init();
   }
 
+  get hasSubscriptions (): boolean {
+    return false;
+  }
+
   isConnected (): boolean {
     return true;
   }

packages/rpc-provider/src/types.ts

@@ -42,6 +42,7 @@ export type ProviderInterface$Emitted = 'connected' | 'disconnected';
 export type ProviderInterface$EmitCb = (value?: any) => any;
 
 export interface ProviderInterface {
+  readonly hasSubscriptions: boolean;
   isConnected (): boolean;
   on (type: ProviderInterface$Emitted, sub: ProviderInterface$EmitCb): void;
   send (method: string, params: Array<any>): Promise<any>;

packages/rpc-provider/src/ws/index.ts

@@ -95,6 +95,13 @@ export default class WsProvider implements WSProviderInterface {
     }
   }
 
+  /**
+   * @summary `true` when this provider supports subscriptions
+   */
+  get hasSubscriptions (): boolean {
+    return true;
+  }
+
   /**
    * @summary Manually connect
    * @description The [[WsProvider]] connects automatically by default, however if you decided otherwise, you may