Add coins to teams and user add/remove route

[mradigen]

This PR adds:

• Field coins to each team, defaulting to 0 on creation.
• Everytime a hint is requested, an amount is deducted from the team's coins. (amount can be set in config.hint_penalty)
• Team will not be allowed to view hints if they do not have the enough coins to do so.
• /api/team/add route creates a user and adds them to a given team. Returns 403 if user already exists in another team.
• /api/team/remove route removes a user from a team. Returns 403, if user is not a part of the selected team.

[mradigen]

@Meetesh-Saini How will we be incrementing the coins? Does solving the CTF reward the team with coins as well as leaderboard points?

[WizzyGeek]

@Meetesh-Saini How will we be incrementing the coins? Does solving the CTF reward the team with coins as well as leaderboard points?

In the 1 week period, it rewards them with just coins for solving challenges

[mradigen]

@Meetesh-Saini How will we be incrementing the coins? Does solving the CTF reward the team with coins as well as leaderboard points?

In the 1 week period, it rewards them with just coins for solving challenges

Got it. I'll implement an optional field called coins to Problem. The field can be set for the first week challenges, while the challenges on the event day would have a coin reward of 0.

[WizzyGeek]

the team's add and remove route needs to check the amount of Users in the team and other stuff, but I am not clear on the business logic for that functionality right now to specify the details myself

[WizzyGeek]

@mradigen get this merged asap, contact @Meetesh-Saini to merge it for you.

[mradigen]

The recent few commits add the following changes:

• Pre-event routes under /api/ctf/pre/ which replicates /api/ctf/
• Splits event problem and pre-event problem models under Problem and PreEventProblem that inherit BaseProblem
• Problem_Pydantic has been changed to BaseProblem_Pydantic
• Normalizes User.tag using .strip().casefold()
• Coins under PreEventProblem is named as points (since it inherits from BaseProblem)
• Added /api/leaderboard

[WizzyGeek]

@mradigen ready to merge?