Handle unhandled FileNotFoundException in XamlStylerConsole.cs

[grochocki]

Description:

Fixes #456

Checklist:

• [x] I have commented my code, particularly in hard-to-understand areas
• [x] My changes generate no new warnings
• [ ] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [ ] I have tested my changes by running the extension in VS2017
• [ ] I have tested my changes by running the extension in VS2019
• [ ] I have tested my changes by running the extension in VS2022
• [ ] If changes to the documentation are needed, I have noted this in the description above