Add snippets for console.time and console.timeEnd for execution time measurements

[janosh]

PR adds snippets:

   "consoleTime": {
     "prefix": "cti",
     "body": "console.time(${1:object});",
     "description": "Sets starting point for execution time measurement"
   },
   "consoleTimeEnd": {
     "prefix": "cte",
     "body": "console.timeEnd(${1:object});",
     "description": "Sets end point for execution time measurement"
   }

[janosh]

I just realized I forgot to document these snippets in the readme's "Console methods" table. Perhaps you can add those in a subsequent commit...

[xabikos]

@janosh no worries. I already did it locally and will push it soon!