Add time_and_date plugin. Use it for timezones and date formats around the bot.

backend/src/data/entities/MemberTimezone.ts

@@ -0,0 +1,14 @@
+import { Column, Entity, PrimaryColumn } from "typeorm";
+
+@Entity("member_timezones")
+export class MemberTimezone {
+  @Column()
+  @PrimaryColumn()
+  guild_id: string;
+
+  @Column()
+  @PrimaryColumn()
+  member_id: string;
+
+  @Column() timezone: string;
+}