Fix consistency issues with Player.m_weapon_level and Player.m_missile_level upgrade levels in MP

[tobiasksu]

Certain weapons in MP (e.g. impulse) have projectiles fired with an upgrade level that doesn't match the player's upgrade level. This results in the HUD showing incorrect weapon variant and adds complications to modded behavior like sniper packets. Correctly assign these values on spawn to increase maintainability of code.