Add fields to get_image_metadata result

[SilensAngelusNex]

Add the description and created fields to ImageMetaResponse so that they will be accessible to callers of get_image_metadata.

Fixes #3053

Sanity check:

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Code changes

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[SilensAngelusNex]

I made the type for created be String, but I'd really like to make it something more structured, like exif::DateTime (which can handle timezones and has sub-second resolution). I'm not really sure what the best way to define would be so that Tera can use it. Ideally, we'd still be able to compare it with < et al, but it seems like Tera doesn't support that so we'd have to provide comparison functions?

LMK if you think there's a better approach here.

[Keats]

I'm not really sure what the best way to define would be so that Tera can use it. Ideally, we'd still be able to compare it with < et al, but it seems like Tera doesn't support that so we'd have to provide comparison functions?

Nope it's not possible, we would need to expose a specific type in the Value enum in Tera for datetimes, I considered it for tera2 but ended up not doing it because it adds lots of complexity to handle all the tz/various libraries. I will add some tests though, eg my_date is after(d=other_date), my_date is before(d=other_date). Not as nice as <, > but good enough

[Keats]

can we bubble those as errors so the user will know which image it's for?

[Keats]

and is an empty value an error?