Add support for solidity prettier

**Name:** `prettier-solidity`
**URL:** https://github.com/prettier-solidity/prettier-plugin-solidity

Currently, there is already support for Solidity linters on ALE. The next step would be to add fixing support, and the easiest way seems to be `prettier-plugin-solidity`. It requires `prettier`, but considering most people use JS/TS for Solidity development, there is a high chance of the developers already have it installed.