ofDirectory::listDir performance improvement

[dimitre]

still a draft. other things to do

• test devices
• implement hidden files

as it breaks api, better to implement in a major version change. 0.12.0 ?

closes #6129

[ofTheo]

Adding this issue for reference: #6129

[ofTheo]

@dimitre going to do a PR just for the sorting speed for #6129

ListDir is still quite slow and I think a PR which doesn't break the api would be good.
I'll add some thoughts to this PR in comments on how we could do that.

EDIT: a big issue is that ofDirectory::files is public, so there isn't really a way to change the type to of::filesystem::path without breaking things for people.

I think maybe let's close this PR for now and revisit after 0.12.0.

[dimitre]

Nice. I think it is possible to update ofDirectory not to open file immediatly. this would speed up everything.

[ofTheo]

sounds good @dimitre! - PR #7509 speeds up sort by quite a bit ( even more for larger directories ) and doesn't change current behavior.