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/lib/uploadx.ts

@@ -0,0 +1,37 @@
+import express from 'express'
+import { buildLogger } from '@server/helpers/logger.js'
+import { getResumableUploadPath } from '@server/helpers/upload.js'
+import { CONFIG } from '@server/initializers/config.js'
+import { LogLevel, Uploadx } from '@uploadx/core'
+import { extname } from 'path'
+
+const logger = buildLogger('uploadx')
+
+const uploadx = new Uploadx({
+  directory: getResumableUploadPath(),
+
+  expiration: { maxAge: undefined, rolling: true },
+
+  // Could be big with thumbnails/previews
+  maxMetadataSize: '10MB',
+
+  logger: {
+    logLevel: CONFIG.LOG.LEVEL as LogLevel,
+    debug: logger.debug.bind(logger),
+    info: logger.info.bind(logger),
+    warn: logger.warn.bind(logger),
+    error: logger.error.bind(logger)
+  },
+
+  userIdentifier: (_, res: express.Response) => {
+    if (!res.locals.oauth) return undefined
+
+    return res.locals.oauth.token.user.id + ''
+  },
+
+  filename: file => `${file.userId}-${file.id}${extname(file.metadata.filename)}`
+})
+
+export {
+  uploadx
+}