Razor LSP: Fix and add tests for known formatting issues

[ajaybhargavb]

Below is a list of known issues so far,

• Cleanup doesn't work well in some cases

@if (true) { <div></div> }

• Newline gets added after @: * (Fixed bug causing extra newline after @: #2807)

    @{
        @:is
    }

• @section formatting is messed up (https://github.com/dotnet/aspnetcore/issues/27710)

• Formats C# inside tags, (no longer repros)

<label for="email" @if (true)
                            {<text>a="b"</text>}>c</label>

• Html attribute formatting not maintained

<textarea name="foo"
          id="foo">@("Foo")
        test</textarea>

• @if inside @if doesn't work well (Fixed nested implicit statement formatting #2829)

@if (true)
{
    @if (true)
    {
        ...
    }
}

• OnTypeFormatting sometimes formats more than the expected range (Fixed by 3rd commit in Support ; and } format on type in mixed scenarios #2585)
• GenerateConstructor code action fails spectacularly in some cases with @functions but not @code, (https://github.com/dotnet/aspnetcore/issues/26501) * 5 Days with the primary motivation being to figure out how to track spans after text edits have occurred.

@code {
    public class Foo { }
}

• NewLines are removed unexpectedly in C# blocks with nested HTML (https://github.com/dotnet/aspnetcore/issues/26836)

• 1041173 (Fixed by LSPfication)

• Newline after a nested C# block causes an exception,

<div>
    <div>
    @if(true)
    {
    }
    
    </div>
</div>

• Multi-line explicit expressions don't format correctly

• Multi-line csharp expression indentation at the start of a block (https://github.com/dotnet/aspnetcore/issues/29200)

@{
    var x = DateTime
            .Now;
}

[ajaybhargavb]

Only 3 more issues remain from the above list and are tracked separately. Closing this.