message: Invalidate IModelConnection after close is called
diff: @@ -68,7 +68,11 @@ export class IModelConnection extends IModel {
  public async close(accessToken: AccessToken): Promise<void> {
  if (!this.iModelToken)
  return;
  + try {
  await IModelGateway.getProxy().close(accessToken, this.iModelToken);
  + } finally {
  + (this.token as any) = undefined; // prevent closed connection from being reused
  + }
  }
  /** Ask the backend to open a standalone iModel (not managed by iModelHub) from a file name that is resolved by the backend.
  @@ -84,7 +88,11 @@ export class IModelConnection extends IModel {
  public async closeStandalone(): Promise<void> {
  if (!this.iModelToken)
  return;
  + try {
  await IModelGateway.getProxy().closeStandalone(this.iModelToken);
  + } finally {
  + (this.token as any) = undefined; // prevent closed connection from being reused
  + }
  }
  /** Execute a query against the iModel.
  