WaitFor compatibility with Node watch processes (non-exiting background process)

## Background and Motivation
If an Aspire `AppHost` needs to particular sequence involving a Node script, this can be problematic.

Allow the state of a resource that is effectively a watch process without an exit to be affected by output text. The desired capability is similar to [`problemMatcher` in VS Code tasks that define an "endsPattern"](https://code.visualstudio.com/docs/editor/tasks#_background-watching-tasks)

Today if you run a Node app (eg. `ng serve`) it seems to prematurely indicate "readiness" while it's still executing. Any output indicating "readiness" is highly variable in nature due to script customizations and frameworks.

## Proposed API

`IResourceBuilder` extension

`WaitFor(IResourceBuilder dependency, string message)`
`WaitForWithMessage(IResourceBuilder dependency, string message)`

## Usage Examples

```csharp
// ng serve / watch
var angularClient = builder.AddNpmApp("client", "./apps/client1", "start");

// something to run only after npm project ready
var otherThing = builder.AddNpmApp("otherThing", "./apps/client2", "start")
.WaitForWithMessage(angularClient, "bundle generation complete");
```

## Alternative Designs

## Risks