Gitter notifications for failing solc-bin nightly build

For some reason I get no notifications for failed nightly builds or sync runs in solc-bin. I have to manually check https://github.com/ethereum/solc-bin/actions from time to time. And even if it worked, the notification should be visible to the whole team.

Set up a notification for failed action runs that goes to the [#solidity-dev channel on Gitter](https://gitter.im/ethereum/solidity-dev).

You can reuse parts of the [`gitter_notify_unless_pr`](https://github.com/ethereum/solidity/blob/v0.8.17/.circleci/config.yml#L34-L72) command we use in our main CI config.