[MC-124805] /scoreboard players enable tab-completes and allows non-player entities selectors

The command /scoreboard players enable tab-completes and allows non-player entities.

Note: This could be intended since it is not causing any problems and internally possibly uses the same format as for players.

Create a trigger objective

/scoreboard objectives add testTrigger trigger

Try enabling it for non-player entities
```
/scoreboard players enable @e[type=!player] testTrigger
```
→ It enabled the trigger for the entities