Bechmark suite changes

[chfast]

1. Fix the extension of files with runtime code, e.g. .code or .evm. Currently all files expect *.inputs are assumed to contain code. This makes it inconvenient to have other files like solidity sources, README, etc.
2. Add new file extension for initcode. The benchmark tools should first create a contract with this initcode and benchmark the deployed code. This should work the same as evmc run --create.
3. Split inputs into individual files *.NAME.input and *.NAME.expected. With this change it is easier to use inputs in other tools, e.g.

   evmc run sha1.code --input sha1.empty.input | grep  "Output:.*$(cat sha1.empty.expected)"
   

4. An input file should be required for execution benchmark.