Improvements to `sm_forcertd` command

[Phil25]

• [ ] Allows to specify time until death
• [ ] Allows to specify unlimited, death-persistent time.
• [ ] Allows to specify custom settings
• [ ] Allows to specify silent mode (no sound and message).

Improved time specification

Currently, sm_forcertd is able to specify custom perk time (ex. sm_forcertd @me godmode 999). This system could be extended to specify more specific time, for example:

• sm_forcertd <target> godmode life Gives Godmode until death,
• sm_forcertd <target> godmode forever Gives Godmode which persists across deaths.

Settings provision

There could be an additional argument through which custom settings can be specified, for example:

• sm_forcertd <target> fasthands "reload:1" Gives Fast Hands, but with unaltered reload time.
• sm_forcertd <target> teamcriticals "range:2000; crits:0" Gives Team Criticals with hugely increased range, but mini-crits instead.
• sm_forcertd <target> powerfulhits forever "multiplier:99" Gives Powerful Hits with 99x increased damage which also persists across death.

Distinguishing the 3rd parameter

1. If it's an integer, life, or forever -> treat as time,
2. otherwise, begin parsing for settings format,
3. on failure, fail the command entirely.