shared: split out ioprio related stuff into ioprio-util.[ch]

No actual code changes, just some splitting out.

src/basic/ioprio-util.c

@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "ioprio-util.h"
+#include "parse-util.h"
+#include "string-table.h"
+
+int ioprio_parse_priority(const char *s, int *ret) {
+        int i, r;
+
+        assert(s);
+        assert(ret);
+
+        r = safe_atoi(s, &i);
+        if (r < 0)
+                return r;
+
+        if (!ioprio_priority_is_valid(i))
+                return -EINVAL;
+
+        *ret = i;
+        return 0;
+}
+
+static const char *const ioprio_class_table[] = {
+        [IOPRIO_CLASS_NONE] = "none",
+        [IOPRIO_CLASS_RT] = "realtime",
+        [IOPRIO_CLASS_BE] = "best-effort",
+        [IOPRIO_CLASS_IDLE] = "idle",
+};
+
+DEFINE_STRING_TABLE_LOOKUP_WITH_FALLBACK(ioprio_class, int, IOPRIO_N_CLASSES);