Migrate server to ESM

Sorry for the very big commit that may lead to git log issues and merge
conflicts, but it's a major step forward:

 * Server can be faster at startup because imports() are async and we can
   easily lazy import big modules
 * Angular doesn't seem to support ES import (with .js extension), so we
   had to correctly organize peertube into a monorepo:
    * Use yarn workspace feature
    * Use typescript reference projects for dependencies
    * Shared projects have been moved into "packages", each one is now a
      node module (with a dedicated package.json/tsconfig.json)
    * server/tools have been moved into apps/ and is now a dedicated app
      bundled and published on NPM so users don't have to build peertube
      cli tools manually
    * server/tests have been moved into packages/ so we don't compile
      them every time we want to run the server
 * Use isolatedModule option:
   * Had to move from const enum to const
     (https://www.typescriptlang.org/docs/handbook/enums.html#objects-vs-enums)
   * Had to explictely specify "type" imports when used in decorators
 * Prefer tsx (that uses esbuild under the hood) instead of ts-node to
   load typescript files (tests with mocha or scripts):
     * To reduce test complexity as esbuild doesn't support decorator
       metadata, we only test server files that do not import server
       models
     * We still build tests files into js files for a faster CI
 * Remove unmaintained peertube CLI import script
 * Removed some barrels to speed up execution (less imports)

server/server/models/oauth/oauth-client.ts

@@ -0,0 +1,63 @@
+import { AllowNull, Column, CreatedAt, DataType, HasMany, Model, Table, UpdatedAt } from 'sequelize-typescript'
+import { AttributesOnly } from '@peertube/peertube-typescript-utils'
+import { OAuthTokenModel } from './oauth-token.js'
+
+@Table({
+  tableName: 'oAuthClient',
+  indexes: [
+    {
+      fields: [ 'clientId' ],
+      unique: true
+    },
+    {
+      fields: [ 'clientId', 'clientSecret' ],
+      unique: true
+    }
+  ]
+})
+export class OAuthClientModel extends Model<Partial<AttributesOnly<OAuthClientModel>>> {
+
+  @AllowNull(false)
+  @Column
+  clientId: string
+
+  @AllowNull(false)
+  @Column
+  clientSecret: string
+
+  @Column(DataType.ARRAY(DataType.STRING))
+  grants: string[]
+
+  @Column(DataType.ARRAY(DataType.STRING))
+  redirectUris: string[]
+
+  @CreatedAt
+  createdAt: Date
+
+  @UpdatedAt
+  updatedAt: Date
+
+  @HasMany(() => OAuthTokenModel, {
+    onDelete: 'cascade'
+  })
+  OAuthTokens: Awaited<OAuthTokenModel>[]
+
+  static countTotal () {
+    return OAuthClientModel.count()
+  }
+
+  static loadFirstClient () {
+    return OAuthClientModel.findOne()
+  }
+
+  static getByIdAndSecret (clientId: string, clientSecret: string) {
+    const query = {
+      where: {
+        clientId,
+        clientSecret
+      }
+    }
+
+    return OAuthClientModel.findOne(query)
+  }
+}