Roslyn: Add refactorings to split and merge nested if statements

[AndriySvyryd]

I frequently need to adjust complex if statements and miss some refactorings that could speed up this process.

For example I would like to be able to invoke a quick action on the first && to split
```C#
if (con1
&& (con2 || !con3)
&& !con4)
{

}

```C#
if (con1)
{
    if ((con2 || !con3)
        && !con4))
    {

    }
}

And a refactoring on the nested if to do the reverse.

[Neme12]

I am working on this.

[jinujoseph]

Awesome, thanks @Neme12

[Neme12]

@jasonmalinowski Can you please close this? The PR was merged.