EGO-L-002 warning

objects created by extension should be destroyed in disable()

Objects assigned in `enable()` are missing matching `.destroy()` calls in `disable()` or its helper methods.

Destroy all objects

• extension.js:480

          this._coreWidget = new St.BoxLayout({
              vertical: true,
              style_class: 'core-stats-card',
              reactive: true,
              can_focus: false,
              track_hover: false,
              x_expand: true,
              y_expand: true
          })

• extension.js:537

          this._mbWidget = new St.BoxLayout({
              vertical: true,
              style_class: 'core-stats-card core-stats-mb-card',
              reactive: true,
              can_focus: false,
              track_hover: false,
              x_expand: true,
              y_expand: false
          })