feature: Add invite maxAge check before attempting to create the invite (#1140)

* Add maxage check & improve maxage parameter check

* Change InvalidOperation to ArgumentOoR

* Remove HasValue check
...since it does it implicitly already.

* Add parameter names & better wording for invite OoR

* Move maxAge check to DiscordRestApiClient for consistency

src/Discord.Net.Rest/DiscordRestApiClient.cs

@@ -978,6 +978,8 @@ namespace Discord.API
             Preconditions.NotNull(args, nameof(args));
             Preconditions.AtLeast(args.MaxAge, 0, nameof(args.MaxAge));
             Preconditions.AtLeast(args.MaxUses, 0, nameof(args.MaxUses));
+            Preconditions.AtMost(args.MaxAge, 86400, nameof(args.MaxAge),
+                "The maximum age of an invite must be less than or equal to a day (86400 seconds).");
             options = RequestOptions.CreateOrClone(options);
 
             var ids = new BucketIds(channelId: channelId);

src/Discord.Net.Rest/Entities/Channels/ChannelHelper.cs

@@ -76,9 +76,13 @@ namespace Discord.Rest
         public static async Task<RestInviteMetadata> CreateInviteAsync(IGuildChannel channel, BaseDiscordClient client,
             int? maxAge, int? maxUses, bool isTemporary, bool isUnique, RequestOptions options)
         {
-            var args = new CreateChannelInviteParams { IsTemporary = isTemporary, IsUnique = isUnique };
-            args.MaxAge = maxAge.GetValueOrDefault(0);
-            args.MaxUses = maxUses.GetValueOrDefault(0);
+            var args = new API.Rest.CreateChannelInviteParams
+            {
+                IsTemporary = isTemporary,
+                IsUnique = isUnique,
+                MaxAge = maxAge ?? 0,
+                MaxUses = maxUses ?? 0
+            };
             var model = await client.ApiClient.CreateChannelInviteAsync(channel.Id, args, options).ConfigureAwait(false);
             return RestInviteMetadata.Create(client, null, channel, model);
         }