globally search for media

[r10s]

this pr allows passing 0 to dc_get_chat_media(), the function returns media from any chat then - similar to dc_search_msgs().

moreover, this pr fixes a minor issue to not return hidden media - and a test (dc_get_chat_media() was completely untested)

closes #3527

[r10s]

one thing @adbenitez pointed out in dev chat, is that this approach does not care for duplicates - in a selector you maybe do not want to have them. however, unless there is a dead-simple approach, to allow UI to move forward, it probably makes sense to care for that at some later point in a subsequent pr. also, there is the rough idea of files deduplication, this may help somehow as well ;)

[Simon-Laux]

api wise I would prefer changing line 583 to chat_id: Option<u32>
and then using map to convert it:

Suggested change

	let chat_id = if chat_id == 0 {
	None
	} else {
	Some(ChatId::new(chat_id))
	};
	let chat_id = chat_id.map(|id| ChatId::new(id));

[Simon-Laux]

that way I can pass null in the js api instead of the number 0 which is a bit more clear IMO

[Simon-Laux]

but not too important, its already ok

[r10s]

api wise I would prefer changing line 583 to chat_id: Option
and then using map to convert it:

feel free to push to this pr or do a subsequent one - i was changing up to the existing api only as i do not want to touch the desktop code at all and keep this pr scoped to the rust core part.

[Simon-Laux]

I mentioned it mostly that you know that its an option too, Option<type> gets translated basically to type | null

[r10s]

rust fmt is unhappy now :)

EDIT: pushed a fix.

[r10s]

k, then let's merge that in to go forward with deltachat/deltachat-ios#1668 :)