Create rust.yml

[DmitrySamoylov]

To make sure that all the code merged into master is valid we add github actions with checks that

• all tests pass
• formatting is valid
• no common mistakes caught by clippy

Also fixed existing warnings from fmt and clippy

[zeenix]

• all tests pass

• formatting is valid

• no common mistakes caught by clippy

pro-tip: If you can list multiple changes, then your commit is likely not atomic enough. Kudos on writing a very good commit log, though. :+1: