message: fix(types): Make name required on transaction class
  This allows the class to implement the interface, where `name` has always been required.
diff: import { getCurrentHub, Hub } from '@sentry/hub';
  -import { TransactionContext } from '@sentry/types';
  +import { Transaction as TransactionInterface, TransactionContext } from '@sentry/types';
  import { isInstanceOf, logger } from '@sentry/utils';
  import { Span as SpanClass, SpanRecorder } from './span';
  /** JSDoc */
  -export class Transaction extends SpanClass {
  - public name?: string;
  +export class Transaction extends SpanClass implements TransactionInterface {
  + public name: string;
  /**
  * The reference to the current hub.
  @@ -29,9 +29,7 @@ export class Transaction extends SpanClass {
  this._hub = hub as Hub;
  }
  - if (transactionContext.name) {
  - this.name = transactionContext.name;
  - }
  + this.name = transactionContext.name ? transactionContext.name : '';
  this._trimEnd = transactionContext.trimEnd;
  }
  