server: add support for local image path loading for server (updated)

[cchadowitz]

Updated server-local-image-loading feature branch with latest master branch changes

This is the same changeset reflected in #16874 but updated to the latest changes in master, as too much had diverged and the prior pull request is stale at this point.

[ngxson]

sorry for delayed response.

I think the approach of specifying absolute path can be quite overkill. We can just reuse the same logic as model save/load, just need to specify the base directory and the input path from API will be the relative path. this will significantly reduce the complexity of the implementation.

I'll make another PR and will close this one

[ngxson]

Please take a look: #17697

[cchadowitz]

Sorry for my delayed response, for some reason I didn't get an email from Github for any of this.

Thanks for adding this feature! I see that there is no file size limit like in my original implementation (or like the remote image case). Is there any need for that or no?

Having the paths be relative doesn't quite match my use case but I think I can work around that for the most part.