Using Conan for dependency resolution has broken README.md generation

Since switching to using Conan to figure out at runtime which packages need to be included in a ci-XXXX image and removing
the static list from ci-XXXX/image.yaml, generation by `aswfdocker dockergen` of the ci-XXXX/README.md no longer works:

- dependencies are no longer listed
- the package itself is incorrectly listed as included

It should be possible to call:

```
conan info . --only requires
```

to get this list, but this has to be done in the context of a container which includes Conan itself.

Start with the `aswfdocker dockergen` entry point and compare generated `ci-XXXX/README.md` output with `ci-XXXX/image.yaml`. Run `conan info . --only requires` inside a container that includes Conan, then verify the README lists dependencies and does not list the package itself.

Written by the indexing model from the issue text.