Popfile: Warn the user when `Tag bot_giant` doesn't exist in a giant bot block

[Windolon]

This is particularly an issue on gate maps, where bots without this tag will be stunned upon gate capture. Valve's standard is to have giant bots be immune to the gate stuns.

Under TFBot or Templates > TemplateName blocks, warn the user that Tag bot_giant doesn't exist when Attributes Miniboss is detected in the same block. The warning message could be "Giant bot will not be immune to gate-capture stuns".