feat(oas) - accurate model OAS representation - F to O (#3210)

### Scope

Models F to O

### What

Refactor OAS for models to accurately represent their shape in API responses.

### Why

About 33% of model fields are not accurately represented in the OAS. Most of the issues are:
- fields that can not be omitted in the response are not declared as `required`
- fields that could return `null` as their value are not declared as `nullable: true`

When using a code generator, these OAS issues would lead to inaccurate response shapes in the generated client.

### How

#### nullable
Fields meeting at least one of the following condition will be represented as `nullable: true` in OAS:
* The field is decorated with `@Column({ nullable: true })`
* The field is decorated with `@OneToOne`, `@ManyToOne`
* The field is decorated with `@DeleteDateColumn`

#### optional
Fields meeting at least one of the following conditions will never be listed as `required` in OAS and will be considered optional and could be omitted in the response:
* The field is decorated with `@OneToOne`, `@ManyToOne`, `@OneToMany`, `@ManyToMany`
* The field is decorated with `@FeatureFlagColumn`
* The field is decorated with `@Column({select: false})`
* The field is representing dynamic values not persisted in the database

Fields not meeting any of the conditions above will be declared as `required` and are expected to be present in the response.

### Test
* Ran OAS validator.
* Ran docs build script.

Expect OAS changes to be reflected in the API documentation.

packages/medusa/src/models/note.ts

@@ -47,47 +47,57 @@ export class Note extends SoftDeletableEntity {
  * description: "Notes are elements which we can use in association with different resources to allow users to describe additional information in relation to these."
  * type: object
  * required:
- *   - value
- *   - resource_type
+ *   - author_id
+ *   - created_at
+ *   - deleted_at
+ *   - id
+ *   - metadata
  *   - resource_id
+ *   - resource_type
+ *   - updated_at
+ *   - value
  * properties:
  *   id:
- *     type: string
  *     description: The note's ID
+ *     type: string
  *     example: note_01G8TM8ENBMC7R90XRR1G6H26Q
  *   resource_type:
- *     description: "The type of resource that the Note refers to."
+ *     description: The type of resource that the Note refers to.
  *     type: string
  *     example: order
  *   resource_id:
- *     description: "The ID of the resource that the Note refers to."
+ *     description: The ID of the resource that the Note refers to.
  *     type: string
  *     example: order_01G8TJSYT9M6AVS5N4EMNFS1EK
  *   value:
- *     description: "The contents of the note."
+ *     description: The contents of the note.
  *     type: string
  *     example: This order must be fulfilled on Monday
  *   author_id:
- *     type: string
  *     description: The ID of the author (user)
+ *     nullable: true
+ *     type: string
  *     example: usr_01G1G5V26F5TB3GPAPNJ8X1S3V
  *   author:
  *     description: Available if the relation `author` is expanded.
+ *     nullable: true
  *     $ref: "#/components/schemas/User"
  *   created_at:
+ *     description: The date with timezone at which the resource was created.
  *     type: string
- *     description: "The date with timezone at which the resource was created."
  *     format: date-time
  *   updated_at:
+ *     description: The date with timezone at which the resource was updated.
  *     type: string
- *     description: "The date with timezone at which the resource was updated."
  *     format: date-time
  *   deleted_at:
+ *     description: The date with timezone at which the resource was deleted.
+ *     nullable: true
  *     type: string
- *     description: "The date with timezone at which the resource was deleted."
  *     format: date-time
  *   metadata:
- *     type: object
  *     description: An optional key-value map with additional details
+ *     nullable: true
+ *     type: object
  *     example: {car: "white"}
  */