Fixed signedness of image size

[Lemongrass3110]

Pull Request Prelude

• I have followed proper Hercules code styling.
• I have read and understood the contribution guidelines before making this PR.
• I am aware that this PR may be closed if the above-mentioned criteria are not fulfilled.

Changes Proposed

Issues addressed:
Image size is 59454, which is > INT16_MAX.
Therefore uint16 should be used.
The rest of the code should also be checked, as it uses int32 instead of int16 in general.

[MishimaHaruna]

Thank you. The rest of the code seems reasonably safe. The only places that could use some improvement are the clif_macro_detector_request_init() and clif_captcha_preview_request_init() functions where the downcast to uint16 occurs.
Not strictly necessary since their input value is originally 16 bit so it should in theory never be larger than that, but to be on the safe side, an Assert_retv(image_size >= 0 && image_size <= UINT16_MAX) would be enough