src/basic: "UidRange" → "UIDRange"

We don't "uncapitalize" parts of an already-capitalized name when concatenating
words. In particular, we had UidRange in basic/uid-range.h and UGIDAllocationRange
in basic/uid-alloc-range.h, which is annoying.

src/sysusers/sysusers.c

@@ -117,7 +117,7 @@ typedef struct Context {
         Set *names;
 
         uid_t search_uid;
-        UidRange *uid_range;
+        UIDRange *uid_range;
 
         UGIDAllocationRange login_defs;
         bool login_defs_need_warning;