game_timer entity and HL2 generic timer HUD element

[Blixibon]

A new entity which shows a timer on the player's HUD. It can be displayed with a caption and use various parameters to control the timer’s behavior.

In the following example, 3 timers with different parameters are shown, with each reducing the player's health by 5 as a generic output:

https://drive.google.com/file/d/13uw0VRfQbKzid7939AZsgZ2ZzniEkvNn/view?usp=sharing

This is designed to be a generic version of team_round_timer from TF2, an entity used to control the round timer. game_timer uses the same I/O/KV syntax and general functionality. This includes the ability to pause, count up or down, etc.

Features specific to game_timer include the ability to specify a warning time, control the progress bar, change the timer’s position on the screen, etc.

This feature will also be available in the TF2 branch, with the unique ability to display multiple timers in that game, although that is not currently present in this PR.

---

PR Checklist

• My PR follows all guidelines in the CONTRIBUTING.md file
• My PR targets a develop branch OR targets another branch with a specific goal in mind

[CoolDude034]

This would be useful, i tried implementing this for my own mod but end up failing

[azzyr]

Additional bug found: The timer HUD does not ever close if using saverestore with an active timer