Add ApiOptions overloads to methods on I(Observable)StarredClient

[alexander-efremov]

Fixes #1163

To-do:

• Add overloads on IStarredClient
• Add overloads on IObservableStarredClient
• Add unit tests for these new methods
• Add integration tests for these new methods

/cc @shiftkey, @ryangribble

[shiftkey]

EDIT: oops, I'd messed up the test and not specified PageCount. Amended below:

[IntegrationTest]
public async Task CanRetrievePagesOfPublicStarWatchers()
{
    var owner = "octokit";
    var name = "octokit.net";

    var firstPageOptions = new ApiOptions
    {
        PageSize = 5,
        PageCount = 1,
        StartPage = 1
    };

    var firstPage = await _fixture.GetAllStargazersWithTimestamps(owner, name, firstPageOptions);

    var secondPageOptions = new ApiOptions
    {
        PageSize = 5,
        PageCount = 1,
        StartPage = 2
    };

    var secondPage = await _fixture.GetAllStargazersWithTimestamps(owner, name, secondPageOptions);
    Assert.Equal(5, firstPage.Count);
    Assert.Equal(5, secondPage.Count);

    Assert.NotEqual(firstPage[0].User.Id, secondPage[0].User.Id);
    Assert.NotEqual(firstPage[1].User.Id, secondPage[1].User.Id);
    Assert.NotEqual(firstPage[2].User.Id, secondPage[2].User.Id);
    Assert.NotEqual(firstPage[3].User.Id, secondPage[3].User.Id);
    Assert.NotEqual(firstPage[4].User.Id, secondPage[4].User.Id);
}

[alexander-efremov]

@shiftkey, sorry, I've forgotten push my commits with integration tests. There are a lot of new ones 👍

[shiftkey]

@dampir good to hear ❤️

[shiftkey]

@dampir this looks good, add in that new integration test and this is good to 🚢

[alexander-efremov]

@shiftkey please rerun Travis, it failed again 😢