Replace dockerized cairo compiler by relying on prebuilt GitHub binaries

[FabijanC]

Since we are removing the Starknet CLI dependency, we can also remove it from our docker image. This means the Cairo compiler would remain the only useful thing in the image. We can also remove that and completely stop depending on the docker image, effectively terminating the need for that extra repo.

The binaries available here under Assets could be downloaded depending on the version specified by the user in their hardhat config file. We would somewhere download the specified binary (the exact asset depending on the user's machine), unpack it, and use it. We could use hardhat's Solidity handling for reference (mainly to see where they download the binaries, if they do so).