[TF2] Prevent taunting while loading the Beggar's Bazooka

[Tkain]

Description

In TF2, if a player taunts while loading rockets into the Beggar's Bazooka, the loaded rockets will only fire after the taunt finishes playing. Using this with a looping taunt effectively allows a Bazooka user to store their loaded rockets for as long as they want and fire them whenever they want. (This doesn't significantly impact gameplay, but it has been used to troll players in friendly scenarios.)

This PR fixes this by not allowing a Bazooka user to taunt while any rockets are loaded into the Bazooka.

This resolves https://github.com/ValveSoftware/Source-1-Games/issues/2703.