blocked ip addresses + block user tool

[owocki]

Description

in between phone calls, i play a game of whack a mole with scammers who keep opening up gitcoin grants with falsified information. they are trying to leverage our platform and brand to raise money, and falsifying grants information in order to do so.

some of the fake grants
https://gitcoin.co/grants/1962/filecoin-is-an-open-source-cloud-storage-marketpl
https://gitcoin.co/grants/1944/consensus-of-the-ethereum-20-protocol
https://gitcoin.co/grants/1941/gitcoin-grants-multisig-donate-round-9
https://gitcoin.co/grants/1940/gitcoin-grants-official-matching-pool-fund

#8305 will help a lot too (thanks graham!), but this PR will reduce the cycle time for blocking these users via whack a mole by

0. one click block user button
1. invalidating all sessions when a user is blocked
2. allowing us to block users by ip address (maybe other browser options down the line, depending on how the hackers evolve we may have to use our anti sybil tech in the future)

Refers/Fixes

https://gitcoin.co/_administrationgrants/grant/ <=== fake grants

Testing

tested locally (both ip blocking + blocking user)