\textbf{} and \textit{} do not work for Russian language

[Aqoolare]

Describe the bug

\textbf{} and \textit{} LaTeX functions do not work for Russian language.

To Reproduce

Steps to reproduce the behavior:

1. Result of <math:TextView x:Name="textView" LaTeX="\textit{привет}" Margin="15, 5"/> will be the same as <math:TextView x:Name="textView" LaTeX="привет" Margin="15, 5"/>
2. But content of <math:TextView x:Name="textView" LaTeX="\textit{hello}" Margin="15, 5"/> will change font attribute

Expected behavior

Latex functions apply to Russian

Environment (please complete the following information):

• Platform: [CSharpMath.Forms]
• Package Version or Commit: [e.g. 0.5.1]
• Device: [Pixel 2 Q 10.0]

[FoggyFinder]

Duplicate of #161

[Happypig375]

Merging issue into #142