Add `userIdType` option to `@JWT` and `@UseSessions` and remove `fetchUser` interface and functions

[LoicPoullain]

Issue

See #1120

Solution and steps

• [x] Add userIdType option and change the interface of UseSessions.
• [x] Add userIdType option and change the interface of JWTxxx.
• [x] Remove the FetchUser interface and the fetchUser functions.

Breaking changes and new features

• The FetchUser interface and all the fetchUser functions have been removed.
• The user option in @JWTxxx and @UseSessions now takes by default a (id: number) => Promise<{ [key: string]: any } | null> by default. If the subject of a JWT (of type string) cannot be converted to a number, then an error is thrown. If the user ID must be a string then add userIdType: 'string' to the options.

  
  // Before
  user: fetchUser(User)
  // After
  user: (id: number) => User.findOneBy({ id }),

// TODO: do the same with user with permissions.

Note on the use of MongoDB with TypeORM v0.3:
```typescript
 import { ObjectId } from 'mongodb';

  @JWTRequired({
    userIdType: 'string',
    user: (id: string) => User.findOneBy({ _id: new ObjectId(id) }),
  })

    @ObjectIdColumn()
    // Do not use
    id: ObjectID;
    // Use
    _id: ObjectID;

Checklist

• [ ] Add/update/check docs (code comments and docs/ folder).
• [x] Add/update/check tests.
• [x] Update/check the cli generators.

[codecov-commenter]

Codecov Report

Merging #1119 (f912ba5) into v3-0-0 (a16759e) will increase coverage by 0.00%. The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           v3-0-0    #1119   +/-   ##
=======================================
  Coverage   98.82%   98.83%           
=======================================
  Files          85       86    +1     
  Lines        1705     1719   +14     
  Branches      408      413    +5     
=======================================
+ Hits         1685     1699   +14     
  Misses         20       20           

Impacted Files	Coverage Δ
packages/core/src/index.ts	0.00% <ø> (ø)
...kages/core/src/sessions/http/check-user-id-type.ts	100.00% <100.00%> (ø)
...e/src/sessions/http/get-session-id-from-request.ts	100.00% <100.00%> (ø)
packages/core/src/sessions/use-sessions.hook.ts	98.82% <100.00%> (+0.02%)	:arrow_up:
packages/core/src/core/config/config.ts	94.28% <0.00%> (+0.05%)	:arrow_up:

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