Integration with SM-CustomStatusHUD

[Phil25]

Nosoop's SM-CustomStatusHUD is great for syncing up HUD updates when multiple plugins are calling them. It's weird that nobody had requested RTD support for it.

Tasks

• SM-CustomStatusHUD is a required compilation dependency.
• SM-CustomStatusHUD is an optional runtime dependency, prefer to use it if detected.
• ConVar sm_rtd2_ignore_custom_status_hud = 0 tells RTD to ignore it regardless and keep using its internal systems.