Add ability to automatically fix targets

[fbecart]

For some targets, a command is available to fix the potential issues.

It is very common with code formatters and linters:

• cargo fmt --all -- --check can be fixed with cargo fmt --all
• eslint can be fixed with eslint --fix

It should be possible to specify a target fix command. This command would be run in case of failure of the build command, if a --fix flag is passed to zinoma, or if a ZINOMA_AUTO_FIX=1 env variable is set. In that case, the result of the fix command would replace the result of the build command.