`eventsource-parser` should be an explicit npm dependency

[arthuraraujo-msft]

eventsource-parser is currently included in the project transitively through the dependency eventsource, which is actually listed in package.json.

It is however used directly in the sdk code:

typescript-sdk/src/client/streamableHttp.ts

Line 4 in 1fd6265

import { EventSourceParserStream } from "eventsource-parser/stream";

We should include all dependencies explicitly to ensure the code keeps working without depending on other packages having them listed as their own dependencies. Also, in flows where sub-dependencies are not installed in the same location as the explicit dependencies, this could lead to a failure.

[arthuraraujo-msft]

Looks like #424 was created to address this.