Fixed inconsistent HL icons

[RedCoffeeMug]

• 32px and 64px Half-Life icons now have the same proportions. #3649 mentioned this.
• Half-Life-Alyx icons now have a y inside the square.

[SmartFinn]

For Half-Life: Alyx icon, I meant something like this:

And which variant do you prefer?

[RedCoffeeMug]

From the link you sent in the issue I prefer one of these two. If there is a variant you prefer I could also do that.