automatically check for attachments and auto-ack

[randomairborne]

attachments usually take long enough to upload that they will always require a defer, so automatically ack'ing them would be good

[laralove143]

i'd like to generalize this to acking if it'd probably fail otherwise, the actual implementation is a bit tricky but im thinking something like this

• make Bot::interaction_handle spawn a thread that waits 2 seconds (optimistically assumes next request will take less than a second) and if no request was sent before, defers the interaction
  • because both defer and Bot::interaction_handle need them, add builder-style ephemeral and update methods to InteractionHandle that use DeferVisibility::Ephemeral and DeferBehavior::Update respectively
    • remove these parameters from defer method, remove defer_component altogether
• add Bot::interaction_handle_manual_defer (i hate the name, ideas?) which has the current behavior
• test race conditions (oh no)

enforcement of safety

it'd probably be more idiomatic to have a InteractionHandle::prepare method instead of two variants of the Bot::interaction_handle method, but that way Bot::interaction_handle has no mention of the possible failures if InteractionClient::prepare isn't called besides documentation, so i think this is something like unwrap and unwrap_unchecked (imagine unwrap methods returning Unwrap<T>: Deref<Target = T> with an unsafe method Unwrap::unchecked)

alternatively, Bot::interaction_handle could take an enum/bool telling whether to handle deferring, but this is a hot method and i think writing out the parameter isnt worth it because many people would avoid Bot::interaction_handle_manual_defer since the point of this lib is to abstract over things

lastly, we could take the opposite approach, adding a InteractionHandle::defer_manually method that cancels the spawned thread, tho it looks the best, it means having the overhead of spawning unnecessary tasks and the complexity of holding a thread handle and making it safely cancel a task