mie: implement an interface system for ops

this system allows dialects to register named interfaces, which are collections of function
pointers. an op can then implement this interface, providing callbacks for the interface's
virtual function pointers.

C code can request a pointer to an op's implementation of a given interface and call
virtual functions with no knowledge required about the op itself. this functonality
will also be extended to types, attributes, and dialects themselves.

mie/interface/interface-definition.c

@@ -0,0 +1,28 @@
+#include <blue/ds/string.h>
+#include <mie/dialect/dialect.h>
+#include <mie/interface/interface-definition.h>
+
+struct mie_interface_definition *mie_interface_definition_create(
+	struct mie_dialect *parent, const char *name)
+{
+	struct mie_interface_definition *out = malloc(sizeof *out);
+	if (!out) {
+		return NULL;
+	}
+
+	memset(out, 0x0, sizeof *out);
+
+	out->if_name = b_strdup(name);
+	if (!out->if_name) {
+		free(out);
+		return NULL;
+	}
+
+	out->if_parent = parent;
+	out->if_size = 0;
+
+	b_rope name_rope = B_ROPE_CSTR(name);
+	mie_id_map_put(&parent->d_interfaces, &out->if_id, &name_rope);
+
+	return out;
+}