Allows the user to resize panes using hotkeys

Changes:
- Adds 4 hotkeys for resizing panes horizontally and vertically
- Updates the config files (default not set)
- Updates the window settings to allow the user to modify the pane
  resize increments

tabby-settings/src/components/windowSettingsTab.component.pug

@@ -66,6 +66,18 @@ h3.mb-3(translate) Window
         step='0.01'
     )
 
+.form-line()
+     .header
+         .title(translate) Pane Resize Increment
+     input(
+         type='range',
+         [(ngModel)]='config.store.appearance.paneResize',
+         (ngModelChange)='saveConfiguration();',
+         min='0.1',
+         max='0.9',
+         step='0.05'
+     )
+
 .form-line(*ngIf='platform.supportsWindowControls')
     .header
         .title(translate) Window frame