[LAYOUT][IMPROVEMENT][REFACTOR] Changes main UI

[philipbrito]

This PR is also needed to support the new directory feature.

Also closes #2192

TODO:

• Show server list view;
• Save sort by preferences for each server;
• Show settings view;
• Change user status;
• Show create new channel view.

FUTHER IMPROVEMENTS

• Show no chat rooms view;
• Show server name instead of its URL on Toolbar;
• Unread on top
• Group by favorites
• Connection state view
• Change view animations