Initial version of the code

[llucax]

• Add more keywords to the project metadata
• Remove the generated dummy code
• Add a typing module with a decorator to disable __init__
• Add a new asyncio module with general purpose async tools
• Add a datetime module with a UNIX_EPOCH constant

[llucax]

I derailed a bit while importing the non-default constructible part :grimacing:

There are still a couple more modules I want to include: math with is_close_to_zero() (but I want to write some basic tests) and collections with Bounds (but I want to get the PR finalized in the SDK first).

[llucax]

@daniel-zullo-frequenz thanks to your comment I found some issues when subclassing, the custom error wasn't used. I updated the PR to use a more consistent default exception (before we used 3 different ones depending on when it was raised) and to fix the issue with subclassing, but looking up for the exception to raise in the base classes if not found in the current class.

I will enable auto-merge.

[llucax]

Thanks, updated!