checkout: fix nested sparse directory diff in sparse index

checkout: fix nested sparse directory diff in sparse index

Add the 'recursive' diff flag to the local changes reporting done by 'git
checkout' in 'show_local_changes()'. Without the flag enabled, unexpanded
sparse directories will not be recursed into to report the diff of each
file's contents, resulting in the reported local changes including
"modified" sparse directories.

The same issue was found and fixed for 'git status' in 2c521b0e49 (status:
fix nested sparse directory diff in sparse index, 2022-03-01)

Signed-off-by: Victoria Dye <vdye@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>