Update typescript.code-snippets

[Jack-Works]

1. Change code snippet throw "$1" to throw new Error("$1"). Throw a string is a bad practice because it will drop the execution stack.
2. Add a new snippet for await of

[mjbvz]

The for await addition looks good but I don't think we should change the throw. This snippet has bee there for a while so changing it may break people's workflows (for example, if you are using it to rethrow an exception)

[Jack-Works]

Hmm how to use it to rethrow exception? It provides a string as default

[mjbvz]

Good point. This looks like an improvement then.

Thanks, this will be in the next VS Code insiders build