Cascade terminate/purge support in GrpcDurableTaskClient

[shivamkm07]

This PR adds support to recursively terminate/purge sub-orchestrations in GrpcDurableTaskClient. It also sets the recursive behavior to be false by default.

Closes: #260

[jviau]

As we now have multiple parameters for terminate, I recommend we do the following:

1. Add TerminateInstanceOptions
2. Make the current abstract method virtual. Default implementation will call one of the new methods we add.
3. Add TerminateInstanceOptions accepting virtual methods
4. Update our clients to override the new options-receiving method.

/// add xmldoc
public record TerminateInstanceOptions
{
    public object? Output { get; init; }

    public bool Recursive { get; init; }
}

new methods:

public virtual Task TerminateInstanceAsync(string instanceId, TerminateInstanceOptions? options, CancellationToken cancellation)
    => throw new NotSupportedException($"{this.GetType()} does not support orchestration termination.");

// this is the formerly abstract method
public virtual Task TerminateInstanceAsync(string instanceId, object? output = null, CancellationToken cancellation = default)
{
    TerminateInstanceOptions? options = output is null ? null : new() { Output = output };
    return this.TerminateInstanceAsync(instanceId, options, cancellation);
}

[shivamkm07]

As we now have multiple parameters for terminate, I recommend we do the following:

1. Add TerminateInstanceOptions
2. Make the current abstract method virtual. Default implementation will call one of the new methods we add.
3. Add TerminateInstanceOptions accepting virtual methods
4. Update our clients to override the new options-receiving method.

/// add xmldoc
public record TerminateInstanceOptions
{
    public object? Output { get; init; }

    public bool Recursive { get; init; }
}

new methods:

public virtual Task TerminateInstanceAsync(string instanceId, TerminateInstanceOptions? options, CancellationToken cancellation)
    => throw new NotSupportedException($"{this.GetType()} does not support orchestration termination.");

// this is the formerly abstract method
public virtual Task TerminateInstanceAsync(string instanceId, object? output = null, CancellationToken cancellation = default)
{
    TerminateInstanceOptions? options = output is null ? null : new() { Output = output };
    return this.TerminateInstanceAsync(instanceId, options, cancellation);
}

I am okay with this change. Just should the new TerminateInstanceOptions method be an abstract method and both GrpcDurableTaskClient and ShimDurableTaskClient implement this method? This is what seems to be followed in other DurableTaskClient methods..

[shivamkm07]

As we now have multiple parameters for terminate, I recommend we do the following:

1. Add TerminateInstanceOptions
2. Make the current abstract method virtual. Default implementation will call one of the new methods we add.
3. Add TerminateInstanceOptions accepting virtual methods
4. Update our clients to override the new options-receiving method.

/// add xmldoc
public record TerminateInstanceOptions
{
    public object? Output { get; init; }

    public bool Recursive { get; init; }
}

new methods:

public virtual Task TerminateInstanceAsync(string instanceId, TerminateInstanceOptions? options, CancellationToken cancellation)
    => throw new NotSupportedException($"{this.GetType()} does not support orchestration termination.");

// this is the formerly abstract method
public virtual Task TerminateInstanceAsync(string instanceId, object? output = null, CancellationToken cancellation = default)
{
    TerminateInstanceOptions? options = output is null ? null : new() { Output = output };
    return this.TerminateInstanceAsync(instanceId, options, cancellation);
}

@jviau Pushed the suggested changes. Please review.

[jviau]

Only a few small comments of recursive default behavior.