Convert #[model(...)] attribute macro to a #[derive(Model)] derive macro

[jonahseguin]

• Convert #[model] attribute macro to #[derive(Model)] derive macro
• Add #[model(mongo(collection = "..."))] attribute helper to the derive macro
• Enforce id field to have type Id<#ident, ? impl IdGuard>
• Enforce (or add?) #[serde(rename = "_id")] to id field for mongo model structs
• Enforce (or add?) #[serde(skip_serializing_if = "musty::prelude::Id::is_none")] to id field for all model structs
• Update filter macro to accept special type for Id type (ex User::filter().id().eq(1) without having to call .into() on the value)