Add "deprecated" setting

[bvssvni]

When a library gets deprecated and replaced with another, it is currently not possible to discover which libraries that needs a replace.

• Requires a replace operation.

[vignesh-sankaran]

How are libraries currently marked as deprecated in Piston?

[vignesh-sankaran]

@bvssvni We can add a maintenance = deprecated field under badge, and can specify which library to replace it with via a custom [package.metadata] field