[Tech Enhancement] Implement standard sizes on `Button` component

### Verified issue does not already exist?

- [X] I have searched and found no existing issue
- [X] I will be providing steps how to reproduce the bug (in most cases this will also mean uploading a demo budget file)

### What happened?

Currently, there is no standard button sizes across the app. This enhancement is to extend the `Button2` component to have a `size` prop which accepts some standard size values:

- small
- medium
- large
- extra-large

These standard sizes should vary between screen sizes e.g. different set of width and height for desktop, tablet, mobile

This change should help make all the buttons more uniform in sizes throughout the app

### Where are you hosting Actual?

None

### What browsers are you seeing the problem on?

_No response_

### Operating System

None