Add an extension for Source Editor to set up readOnly instance

Due to gradually increasing interest in using the Source Editor for rendering the files, it is worth creating a separate extension to set up the editor for these usecases.

Potential features:

• Set the readOnly: true option
• Set up the set of options to get rid of unnecessary UI elements that are not useful for readOnly mode
• Fix text selection on mobile devices
• Setting the height of the instance, based on the content instead of the fixed 500px