tool_cb_hdr: allow etag and content-disposition for 3xx reply

tool_cb_hdr: allow etag and content-disposition for 3xx reply

- Parse etag and content-disposition headers for 3xx replies.

For example, a server may send a content-disposition filename header
with a redirect reply (3xx) but not with the final response (2xx).
Without this change curl would ignore the server's specified filename
and continue to use the filename extracted from the user-specified URL.

Prior to this change, 75d79a4 had limited etag and content-disposition
to 2xx replies only.

Tests-by: Daniel Stenberg
Reported-by: Morgan Willcock
Fixes https://github.com/curl/curl/issues/13302
Closes #13484