selftests/hid: tablets: reduce the number of pen state

All the *_WITH*BUTTON states were almost identical except for the
button itself.

I need to add a new device with a third button, and adding a bunch of
states is going to be quite cumbersome.

So convert the `button` parameter of PenState as a boolean, and store
which button is the target as an argument to all functions that need it.

Link: https://lore.kernel.org/r/20240410-bpf_sources-v1-12-a8bf16033ef8@kernel.orgReviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>