tree-wide: never use the off_t unless glibc makes us use it

off_t is a really weird type as it is usually 64bit these days (at least
in sane programs), but could theoretically be 32bit. We don't support
off_t as 32bit builds though, but still constantly deal with safely
converting from off_t to other types and back for no point.

Hence, never use the type anymore. Always use uint64_t instead. This has
various benefits, including that we can expose these values directly as
D-Bus properties, and also that the values parse the same in all cases.

src/import/pull-raw.c

@@ -314,7 +314,7 @@ static int raw_pull_make_local_copy(RawPull *i) {
         if (r < 0)
                 log_warning_errno(errno, "Failed to set file attributes on %s: %m", tp);
 
-        r = copy_bytes(i->raw_job->disk_fd, dfd, (off_t) -1, true);
+        r = copy_bytes(i->raw_job->disk_fd, dfd, (uint64_t) -1, true);
         if (r < 0) {
                 unlink(tp);
                 return log_error_errno(r, "Failed to make writable copy of image: %m");