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)

client/src/app/shared/shared-instance/instance-about-accordion.component.ts

@@ -1,8 +1,7 @@
 import { Component, EventEmitter, Input, OnInit, Output, ViewChild } from '@angular/core'
 import { HooksService, Notifier } from '@app/core'
 import { NgbAccordionDirective } from '@ng-bootstrap/ng-bootstrap'
-import { ClientFilterHookName, PluginClientScope } from '@shared/models/plugins'
-import { About } from '@shared/models/server'
+import { About, ClientFilterHookName, PluginClientScope } from '@peertube/peertube-models'
 import { InstanceService } from './instance.service'
 
 @Component({

client/src/app/shared/shared-instance/instance-features-table.component.ts

@@ -1,7 +1,7 @@
 import { Component, OnInit } from '@angular/core'
 import { ServerService } from '@app/core'
 import { formatICU } from '@app/helpers'
-import { ServerConfig } from '@shared/models'
+import { ServerConfig } from '@peertube/peertube-models'
 
 @Component({
   selector: 'my-instance-features-table',

client/src/app/shared/shared-instance/instance-follow.service.ts

@@ -4,8 +4,8 @@ import { catchError, concatMap, toArray } from 'rxjs/operators'
 import { HttpClient, HttpParams } from '@angular/common/http'
 import { Injectable } from '@angular/core'
 import { RestExtractor, RestPagination, RestService } from '@app/core'
-import { arrayify } from '@shared/core-utils'
-import { ActivityPubActorType, ActorFollow, FollowState, ResultList, ServerFollowCreate } from '@shared/models'
+import { arrayify } from '@peertube/peertube-core-utils'
+import { ActivityPubActorType, ActorFollow, FollowState, ResultList, ServerFollowCreate } from '@peertube/peertube-models'
 import { environment } from '../../../environments/environment'
 import { AdvancedInputFilter } from '../shared-forms'
 

client/src/app/shared/shared-instance/instance.service.ts

@@ -3,9 +3,8 @@ import { catchError, map } from 'rxjs/operators'
 import { HttpClient } from '@angular/common/http'
 import { Injectable } from '@angular/core'
 import { MarkdownService, RestExtractor, ServerService } from '@app/core'
-import { objectKeysTyped } from '@shared/core-utils'
-import { peertubeTranslate } from '@shared/core-utils/i18n'
-import { About } from '@shared/models'
+import { objectKeysTyped, peertubeTranslate } from '@peertube/peertube-core-utils'
+import { About } from '@peertube/peertube-models'
 import { environment } from '../../../environments/environment'
 
 export type AboutHTML = Pick<About['instance'],