Selectors targetting players in /title commands erroneously prints their UUID instead of display name

Verification builds: Release 809752

Summary: Using selectors which target players (such as `@a` or `@e[type=player]`) in title commands (title, subtitle and actionbar)

Impact: This makes it impossible to display a player name in titles, for example to display "<player> won the game!" or anything that intends to print a player name in a title command.

What is the impact to players/partners if we don't fix? It will no longer be possible to mention a specific player in /title commands. A current project of mine is affected by this issue, and I heard of other partners/devs mentioning this.

Repro Steps:

1. Run any title command with a selector that targets a player as its contents, i.e `title @a title @p`

Observed Results: It prints the player's UUID

Expected Results: It prints the player's display name

Screenshots/Videos attached: Yes