Support video views/viewers stats in server

* Add "currentTime" and "event" body params to view endpoint
 * Merge watching and view endpoints
 * Introduce WatchAction AP activity
 * Add tables to store viewer information of local videos
 * Add endpoints to fetch video views/viewers stats of local videos
 * Refactor views/viewers handlers
 * Support "views" and "viewers" counters for both VOD and live videos

server/middlewares/cache/shared/api-cache.ts

@@ -6,8 +6,8 @@ import { OutgoingHttpHeaders } from 'http'
 import { isTestInstance, parseDurationToMs } from '@server/helpers/core-utils'
 import { logger } from '@server/helpers/logger'
 import { Redis } from '@server/lib/redis'
-import { HttpStatusCode } from '@shared/models'
 import { asyncMiddleware } from '@server/middlewares'
+import { HttpStatusCode } from '@shared/models'
 
 export interface APICacheOptions {
   headerBlacklist?: string[]
@@ -152,7 +152,7 @@ export class ApiCache {
       end: res.end,
       cacheable: true,
       content: undefined,
-      headers: {}
+      headers: undefined
     }
 
     // Patch express