feat(http-ratelimiting): add Bucket::new (#2026)

Add `Bucket::new` to allow users to construct buckets, necessary for
implementing the `Ratelimiter` trait's `bucket` method. This was a gap
in the API that made the trait unable to be implemented.

Author: MatthieuCoder

Diff for: twilight-http-ratelimiting/src/in_memory/mod.rs

@@ -113,13 +113,14 @@ impl Ratelimiter for InMemoryRatelimiter {
                 || Box::pin(future::ok(None)),
                 |bucket| {
                     let started_at = bucket.started_at.lock().expect("bucket poisoned");
-
-                    Box::pin(future::ok(Some(InfoBucket {
-                        limit: bucket.limit(),
-                        remaining: bucket.remaining(),
-                        reset_after: Duration::from_millis(bucket.reset_after()),
-                        started_at: *started_at,
-                    })))
+                    let reset_after = Duration::from_millis(bucket.reset_after());
+
+                    Box::pin(future::ok(Some(InfoBucket::new(
+                        bucket.limit(),
+                        bucket.remaining(),
+                        reset_after,
+                        *started_at,
+                    ))))
                 },
             )
     }

Diff for: twilight-http-ratelimiting/src/lib.rs

@@ -53,6 +53,28 @@ pub struct Bucket {
 }
 
 impl Bucket {
+    /// Create a representation of a ratelimiter bucket.
+    ///
+    /// Buckets are returned by ratelimiters via [`Ratelimiter::bucket`] method.
+    /// Its primary use is for informational purposes, including information
+    /// such as the [number of remaining tickets][`Self::limit`] or determining
+    /// how much time remains
+    /// [until the bucket interval resets][`Self::time_remaining`].
+    #[must_use]
+    pub const fn new(
+        limit: u64,
+        remaining: u64,
+        reset_after: Duration,
+        started_at: Option<Instant>,
+    ) -> Self {
+        Self {
+            limit,
+            remaining,
+            reset_after,
+            started_at,
+        }
+    }
+
     /// Total number of tickets allotted in a cycle.
     #[must_use]
     pub const fn limit(&self) -> u64 {