Modularised code into packages/crates

[CLAassistant]

All committers have signed the CLA.

[chughts]

I've asked @ibmmqmet to review.

@supplanter-wood Could you please read and sign the CLA.

[ibmmqmet]

Need to fix compile warnings in Delete program

warning: unused import: `std::io`
 --> src/file.rs:4:5
  |
4 | use std::io;
  |     ^^^^^^^
  |

[ibmmqmet]

Trying to work out what the point of this is. There's no description as to why there is such a large change with everything being split into separate files. It's making it a lot harder to read and work through what is meant to be a trivial example.

[supplanter-wood]

It was an attempt to tidy up the code, however I understand from an example point of view it is beneficial to keep all the code within one file.