Refactor load_image

[emirkmo]

load_image now contains sites/instruments, as well as the FlowsImage dataclass. This should all be refactored out of load_image.

[emirkmo]

Currently, the instrument and FlowsImage classes do not obey Open/Close principle at a minimum. So that should also be fixed.

[emirkmo]

basic refactor is done and working on devel. Need to test vs. the larger archive.