Update icon names

The ShinyGR() function returns the following warning messages.
The ui.R and the server.R files need to be updated.

This Font Awesome icon ('sync') does not exist:
* if providing a custom `html_dependency` these `name` checks can 
  be deactivated with `verify_fa = FALSE`
This Font Awesome icon ('th') does not exist:
* if providing a custom `html_dependency` these `name` checks can 
  be deactivated with `verify_fa = FALSE`
This Font Awesome icon ('question-circle') does not exist:
* if providing a custom `html_dependency` these `name` checks can 
  be deactivated with `verify_fa = FALSE`
This Font Awesome icon ('sync') does not exist:
* if providing a custom `html_dependency` these `name` checks can 
  be deactivated with `verify_fa = FALSE`