Reaction codec libxmtp integration

[cameronvoell]

Demonstrates XIP-38: Queryable Content Fields (naming still in progress )

See new rust bindings function and test below:

#[derive(uniffi::Record)]
pub struct FfiMessageWithReactions {
    pub message: FfiMessage,
    pub reactions: Vec<FfiMessage>,
}

pub async fn find_messages_with_reactions(
        &self,
        opts: FfiListMessagesOptions,
    ) -> Result<Vec<FfiMessageWithReactions>, GenericError> {
        let delivery_status = opts.delivery_status.map(|status| status.into());
        let direction = opts.direction.map(|dir| dir.into());
        let kind = match self.conversation_type()? {
            FfiConversationType::Group => None,
            FfiConversationType::Dm => Some(GroupMessageKind::Application),
            FfiConversationType::Sync => None,
        };

        let messages: Vec<FfiMessageWithReactions> = self
            .inner
            .find_messages_with_reactions(
                &MsgQueryArgs::default()
                    .maybe_sent_before_ns(opts.sent_before_ns)
                    .maybe_sent_after_ns(opts.sent_after_ns)
                    .maybe_kind(kind)
                    .maybe_delivery_status(delivery_status)
                    .maybe_limit(opts.limit)
                    .maybe_direction(direction),
            )?
            .into_iter()
            .map(|msg| msg.into())
            .collect();
        Ok(messages)
    }

Test code: https://github.com/xmtp/libxmtp/pull/1345/files#diff-3a24c3e76565487a710ac9863ac05160128f4f90892e07849b555a6de43a6e8fR4495-R4591

[insipx]

I like the direction of these content types, seems like a natural progression to introduce them as another crate library

Looking over this stuff, the only thing I find off is to introduce migrations and call into xmtp_mls just for database operations. WDYT about splitting the store stuff into its own crate, xmtp_db or something like that? Maybe its out of scope for this XIP/feature, though.