Introduce DataSource class

[turbaszek]

Description
Currently all data sources supported by Kibble are defined in this one, long yaml:
https://github.com/apache/kibble/blob/8904f39ca2b19aef3522455ec357294cc398c49e/kibble/api/yaml/sourcetypes.yaml#L1-L103

We should introduce DataSource base class and then rewrite (automatically) the yaml file into pythonic code. For example:

class GitDataSource(DataSource):
    title: str = "Plain git repository"
    description: str = "This is a plain git repository with no issues/PRs attached. For GitHub repositories, use the GitHub source type."
    regex: str = r"(?:https?|git)://.*/.+\.git"
    example: str = "git://example.org/repos/foo.git"
    optauth: List[str] = [
        "username",
        "password",
    ]

This will also bring us closer to refactoring API - having a DataSource class we can implement common update, delete, create methods that will be used by /api/sources endpoint.

Use case
To make it easier to work with data sources and keep them as pythonic object not yaml files.

Related Issues
N/A