Add support for empty lines above and below multiline comments

[xEsteem]

In our XAML files we have copyright headers which we want to look something like this

<!--
    <copyright>
        etc etc
    </copyright>
-->

When you save the file using XAML Styler, it forces the trailing comment symbol onto the copyright close line

<!--
    <copyright>
        etc etc
    </copyright>-->

Would like to be able to configure XAML styler to wrap multiline comments with the <!--- and --> on new lines from the comment