Request: .Should().PushAnySatisfying(..)

### Description

Just started using FA.Reactive and it's awesome, great work!

I have a suggestion for an assertion similar to `SatisfyRespectively` for collection assertions: `PushAnySatisfying`

#### Use Case

I am looking for an occurrence of a particular element that satisfies some constraints. I don't care about the ordering, hence the `Any` of `PushAnySatisfying`.

Example usage:

```csharp
observable.Observe()
.Should()
.PushAnySatisfying(e => {
e.Property.Should().Be("value");
e.OtherProperty.Should().Be("other value");
});
```

该 issue 未指出实现文件或测试路径。首先定位现有的 collection assertion 和 SatisfyRespectively 实现，然后为满足所提供 assertions 的无序元素添加测试覆盖；当示例用法能够正常工作且新行为经过测试后，即视为完成。

由索引模型根据 Issue 内容生成。