Add timely reminder button*

* Add a check in Timely command that removes the reminder button if there already is a timely reminder in DB.
* Add ReminderType in db/models. As well as migrations.
* Set Normal reminders to be of `ReminderType.User`, and Timely reminders to be of `ReminderType.Timely`

src/NadekoBot/Migrations/Sqlite/20230813110732_timely-reminder-type.cs

@@ -0,0 +1,29 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace NadekoBot.Db.Migrations.Sqlite
+{
+    /// <inheritdoc />
+    public partial class timelyremindertype : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<int>(
+                name: "Type",
+                table: "Reminders",
+                type: "INTEGER",
+                nullable: false,
+                defaultValue: 0);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "Type",
+                table: "Reminders");
+        }
+    }
+}

src/NadekoBot/Migrations/Sqlite/SqliteContextModelSnapshot.cs

@@ -1648,6 +1648,9 @@ namespace NadekoBot.Db.Migrations.Sqlite
                     b.Property<ulong>("ServerId")
                         .HasColumnType("INTEGER");
 
+                    b.Property<int>("Type")
+                        .HasColumnType("INTEGER");
+
                     b.Property<ulong>("UserId")
                         .HasColumnType("INTEGER");