Support creation of LVGL groups

**Describe the problem you have/What new integration you would like**

I need to assign different [LVGL groups](https://docs.lvgl.io/8.4/overview/indev.html#groups) to different widgets, but ESPHome provides no way to create groups other than assigning one to the keypad or encoder. But you can only assign one group.

We also need a way to update the group assigned to a keypad, but that's doable with [`lv_indev_set_group`](https://github.com/lvgl/lvgl/blob/e8b95b3f9c91a8b186d5705cb7705c72e6f5aea7/src/core/lv_indev.h#L84) in C++ relatively easily, though an action would be helpful.

**Please describe your use case for this integration and alternatives you've tried:**

Multiple groups are needed if you don't want focus to jump across pages or tabs.

**Additional context**