basic: rename cap-list.c -> capability-list.c

This also renames relevant files in the same way.

Addresses https://github.com/systemd/systemd/pull/37904#discussion_r2191950396

src/basic/capability-list.h

@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include "forward.h"
+
+/* Space for capability_to_string() in case we write out a numeric capability because we don't know the name
+ * for it. "0x3e" is the largest string we might output, in both sensese of the word "largest": two chars for
+ * "0x", two bytes for the hex value, and one trailing NUL byte. */
+#define CAPABILITY_TO_STRING_MAX (2 + 2 + 1)
+
+const char* capability_to_name(int id);
+const char* capability_to_string(int id, char buf[static CAPABILITY_TO_STRING_MAX]);
+#define CAPABILITY_TO_STRING(id) capability_to_string(id, (char[CAPABILITY_TO_STRING_MAX]) {})
+
+int capability_from_name(const char *name);
+int capability_list_length(void);
+
+int capability_set_to_string(uint64_t set, char **ret);
+int capability_set_to_string_negative(uint64_t set, char **ret);
+int capability_set_to_strv(uint64_t set, char ***ret);
+int capability_set_from_string(const char *s, uint64_t *ret);