refspec: relocate refname_matches_negative_refspec_item

refspec: relocate refname_matches_negative_refspec_item

Move the functions `refname_matches_negative_refspec_item()`,
`refspec_match()`, and `match_name_with_pattern()` from `remote.c` to
`refspec.c`. These functions focus on refspec matching, so placing them
in `refspec.c` aligns with the separation of concerns. Keep
refspec-related logic in `refspec.c` and remote-specific logic in
`remote.c` for better code organization.

Signed-off-by: Meet Soni <meetsoni3017@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>