Ability to specify more than one active page for touchscreen sensors

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

I'd like to be able to create a touchscreen button that is reused on more than one page (but not on all pages). Perhaps the "page_id" attribute in the YAML would be able to accept a space or comma-separated list of pages to operate on?

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

There are situations where it would be extremely convenient for the touchscreen binary_sensor platform to have the ability to specify more than one page_id for the sensor to be active on. For example, a "return" button could be drawn on the multiple "sub" pages which would perform the same act of returning the user to the main page in the UI. The return button should **not** be drawn on the main UI page itself, so simply allowing it to exist on all pages is not a good solution.

**Additional context**

A proposed configuration example for this feature could be (proposed syntax change in parenthesis):
```
binary_sensor:
- platform: touchscreen
name: Return Button
id: return_button
page_id: details (settings credits eyecandy)
....
```

Start by locating the touchscreen binary_sensor configuration and the page_id handling in ESPHome. Check how a sensor is currently activated and rendered for one page, then define how a space- or comma-separated list should behave; done means the return button appears on each listed page and not on other pages.

Written by the indexing model from the issue text.