Refactor + combine giveXP commands

[cmontminy]

There are currently like three different giveXP commands and I'm not sure why. We can get away with one command that functions something like !giveXP [amount] [list of members @s, ex: @cake @daniel @rushi @avi]

• One command, remove other giveXP like commands
• Ensure that only admins can use it
• Make it so that it can have any number of args to allow for a long list of members
• Make first arg always be the amount of XP to give, throw an error if this field is skipped
• Confirm the message was successful somehow, probably with the bot giving an emoji reaction to the original command message