Migrate `rutie-derive` and `rutie-derive-macros` to `rutie

[Hywan]

See danielpclark/rutie#145 for the context.

The idea is to migrate rutie-derive and rutie-derive-macros inside rutie itself. The crates must be polished first I reckon. The question is: Where do we polish it? Here, or inside rutie?

[ilyazub]

@Hywan I'm working on a PR with migration. I've copied source files of rutie-derive and rutie-derive-macros to the newly created rutie/src/dsl folder and moved rutie/src/dsl.rs to rutie/src/dsl/mod.rs. I want to keep the directory structure of rutie with the least possible changes.

Not sure it's the best approach. Currently fixing compilation errors.

Maybe a better option is move rutie/src/* to rutie/crates/rutie and copy crates/{rutie-derive,rutie-derive-macros} from this repository to rutie/crates/. Similar to what you've done here.

What do you think?