Add stacktrace link for .net

[brianthi]

Bruno's team has done the backend work to generate the stack trace link. The remaining work would to be to show the stack trace link in the app.

AC:

• The backend API which returns the source link to the frontend, should modify the URL in the following way:
  -- If the URL points to github raw content domain, change that domain to github.com
  -- Add the line numbers for the stack trace frame to the end of the URL so that the link can take the user directly to the line which the error was thrown
• If the customer has a source code management tool installed for their org, use it to see if we can find a stack trace link.
  -- If no link can be found for any reason including missing code mappings, then link the user to the source link, and don't show the prompt to add code mappings
• For non-github source link URLs, never show those as stack trace links in our UI.
• Add to the docs that we support this feature for .net, and frameworks supported by the .net SDK.