Add save and check buttons to the settings sidebar

[CloneWith]

Could consider adding two buttons to the settings section of the injector:

• Save Changes: In place of automatic update on textbox's commit event. Trigger configuration update manually by the user, which could effectively reduce the restart notification spam.
• Check Availability: Give users a chance to test their specified links before actually applying changes on next launch. This could be achieved either by using the API interface given by the game, or building a request from scratch by ourselves.