Expose wlr_edges enum from wlroots

[acrisci]

This enum is for the edges of things in wlroots here.

enum wlr_edges {
	WLR_EDGE_NONE = 0,
	WLR_EDGE_TOP = 1,
	WLR_EDGE_BOTTOM = 2,
	WLR_EDGE_LEFT = 4,
	WLR_EDGE_RIGHT = 8,
};

Needed for resize operations and other things.

Do you want to expose it directly as a C enum or wrap it with bitflags?

[Timidger]

Let's expose it as bitflags, since that's more ergonomic for the end user to work with. Repr(c) enums are for FFI and but are less ergonomic/rustic to work with