Update exit-future and make sc-cli compile on wasm (#4289)

* updated exit-future (github repo)

* Switch to broadcast crate

* Migrate client/cli

* Switch exit-future to modernize branch

* Small changes

* Switch to cargo version and fix fg tests

* Revert "Small changes"

This reverts commit a488106805d220cb4aee9e46a71481424c6d87d5.