RH-22 Backend - Add migrations and seeding data with TypeORM

[miguel-square]

Issue: https://royal-hostels.atlassian.net/browse/RH-22

Adds scripts to generate and run migrations.

Adds seeding data for:

• amenities
• properties
• rooms
• property types
• relations between property types and properties
• relations between properties and rooms
• relations between properties and amenities

• relations between rooms and amenities

  Relevant scripts:

npm run mig-gen -- src/shared/db/migrations/<name of migration> to generate migration

npm run mig-gen:init generates a migration ending with -init.ts

npm run mig-run run pending migrations

npm run seed run seeding