input: rewrite of how we match foot’s own key bindings

Bindings are matched in one out of three ways:

* By translated (by XKB) symbols
* By untranslated symbols
* By raw key codes

A translated symbol is affected by pressed modifiers, some of which
can be “consumed”. Consumed modifiers to not partake in the comparison
with the binding’s modifiers. In this mode, ctrl+shift+2 maps to
ctrl+@ on a US layout.

Untranslated symbols, or un-shifted symbols refer to the “base” symbol
of the pressed key, i.e. it’s unaffected by modifiers. In this mode,
consumed modifiers *do* partake in the comparison with the binding’s
modifiers, and ctrl+shift+2 maps to ctrl+shift+2 on a US layout.

More examples: ctrl+shift+u maps to ctrl+U in the translated lookup,
while ctrl+shift+u maps to ctrl+shift+u in the untranslated lookup.

Finally, we also match raw key codes. This allows our bindings to work
using the same physical keys when the user switches between latin and
non-latin layouts.

This means key bindings in foot.ini *must* not include both +shift+
and a *shifted* key. I.e. ctrl+shift+U is not a valid combo as it
cannot be triggered. Unfortunately, this was how you were supposed to
write bindings up until now... so, we try to detect such bindings, log
a deprecation warning and then “fix” the binding for the user.

When specifying bindings in foot.ini, both ctrl+U and ctrl+shift+u are
valid, and will work. The latter is preferred though, since we cannot
detect the raw key code for the former variant. Personally, I also
prefer the latter one because it is more explicit; it’s more obvious
which keys are involved.

However, in some cases it makes more sense to use the other
variant. Typically for non-letter combos.

url-mode.h

@@ -20,4 +20,6 @@ void urls_render(struct terminal *term);
 void urls_reset(struct terminal *term);
 
 void urls_input(struct seat *seat, struct terminal *term, uint32_t key,
-                xkb_keysym_t sym, xkb_mod_mask_t mods, uint32_t serial);
+                xkb_keysym_t sym, xkb_mod_mask_t mods, xkb_mod_mask_t consumed,
+                const xkb_keysym_t *raw_syms, size_t raw_count,
+                uint32_t serial);