Allow project-specific configuration

[tarkatronic]

🚀 Feature Request

Is your feature request related to a problem? Please describe.

Right now, all ownership information for projects is determined automatically based on the permissions for a GitHub repository. This works well for many projects, but some need to have more restrictive permissions because of wider shared project ownership. It should be possible to override the detected ownership on a case-by-case basis for projects like those.

This could also absolutely lead to configuring other elements of a project via the config file.

Describe the solution you'd like

It should be possible to define project sections in the config file, along the lines of:

[[project]]
name = "Vulnbot"
owners = [
  "team-a", "team-b", "team-c"
]
  [[source]]
  datasource = "github"
  name = "vulnbot"

This would be represented by a data structure like:

type ProjectSource struct {
    Datasource string
    Name string
}
type ProjectConfig struct {
    Name string
    Owners []string
    Source []ProjectSource
}

Describe alternatives you've considered

Ultimately it would be good to be able to configure what datasource the ownership information comes from, now that there are multiple datasources, but I think this will be necessary regardless as a per-project override.