Refactor: use index files and short import paths.

src/components/popover/tab/index.ts

@@ -0,0 +1,7 @@
+export * from './tab';
+export { KeymapTabComponent } from './keymap';
+export { KeypressTabComponent } from './keypress';
+export { LayerTabComponent } from './layer';
+export { MacroTabComponent } from './macro';
+export { MouseTabComponent } from './mouse';
+export { NoneTabComponent } from './none';