Conan 2.0 migration for recipes

Conan 2.0 will require some changes in the recipes:

https://docs.conan.io/en/latest/conan_v2.html

- self.dependencies to access information about dependencies
- Commands that disappear in 2.0: copy
- Use generators and helpers only from conan.tools.xxxx space. All the other ones are going to be removed.
- Use the from conan import ConanFile import instead of the legacy from conans ...