From: ZheNing Hu <adlternative@gmail.com>

Because sometimes we want to check if the files in the
index match the sparse specification by using
`git ls-files -t`, but `-t` option have semi-deprecated,

So introduce "%(skipworktree)" atom to git ls-files
`--format` option. When we use this option, if the file
match the sparse specification and removed from working
tree, it will output "yes", othewise, output "no".

Signed-off-by: ZheNing Hu <adlternative@gmail.com>

Submitted-As: https://lore.kernel.org/git/pull.1458.git.1673451741587.gitgitgadget@gmail.com