Replace current KZ mode with SimpleKZ

[zer0k-z]

Changes:

• Remove stamina from current KZ gamemode.
• Add CSGO's SimpleKZ movement tweaks (prestrafe and bhop).
• Remove sliding at speed over 250 and move KZ tickrate to 128 in order for SKZ to be functional
• Re-add ledgegrabbing (sv_considered_on_ground 2.0)
• Modify "Last Jump Modifier" to SKZ takeoff velocity... this is a bit scuffed.
• Give knife and pistol to KZ players.

Difference:

• Player jump height is always 57.0 instead of 55.8 and only 57.0 when crouch jumped in CSGO.
• However, player crouch height boost is 8.5 instead of 9.0 in CSGO, making 66s impossible in this game.
• This ultimately adds one tick of air time compared to CSGO, increase your jump distance by 2.5 to 3 units.
• Landing while ducked does not immediately clamp player speed like CSGO.
• CSGO's bhop takeoff speed is delayed by one tick, this is not the case here.

Bugs:

• Saveloc doesn't save prestrafe variables.
• Tickrate can't be correctly set to 128, only possible through console. (fixed)

Checklist

• I have thoroughly tested all of the code I have modified/added/removed to ensure something else did not break
• If there is a localization token change, I have updated the momentum_english_ref.res file with the changes, ran tokenizer.py to generate an up-to-date localization file, and have committed both the .res file changes and the new localization .txt file
• If I introduced new h/cpp files, I have added them to the appropriate project's VPC file (server_momentum.vpc / client_momentum.vpc / etc)
• If I have added or modified any visual assets (models, materials, panels, effects, etc), I have taken screenshots / videos of them and attached them to this PR directly (screenshots uploaded through github, videos uploaded to youtube and linked)
• If I have modified any console command, console variable, or momentum entity, I have opened an issue (or a PR) for it in the Momentum Mod documentation repository
• My commits are relatively small and scoped to the best of my ability
• My branch has a clear history of changes that can be easy to follow when being reviewed commit-by-commit
• My branch is functionally complete; the only changes to be done will be those potentially requested in code review

[Gocnak]

Just asking, is any of this code yoinked directly from the SKZ repository?

I ask because SKZ (and all of GOKZ) things are licensed under the GPL license, which does not work with our mandatory closed source code structure now.

It's unfortunate, but if possible, we can reach out to the GOKZ team to either obtain the right to use the code under the LGPL (or a different, like MIT) license. Otherwise we can't accept this PR, at least not into the Chaos codebase.

[zer0k-z]

I didn't think about this problem when I was making the PR... The prestrafe and bhop code is yoinked directly from the SKZ repo, so unfortunately this might be slightly complicated.

[Gocnak]

For now you can continue to use it, we will talk to the SKZ developers and see about potentially being granted a more permissive license. I'll hold off on merging until we get a response in regards to it.