OpenAPI 3.1.0 and separate Attribute namespace

Main feature is a switch to OpenAPI 3.1.0 wih support for summary/description next to $ref.

Another change is to move attributes into their own namespace OpenAPI\Attributes which solves warnings from
static analysers and does make the code more maintainable.

Finally. named arguments for attributes extending from Schema have been clean up and updated.

What's Changed

• Split of annotations and attributes by @DerManoMann in #1024
• Update attribute namespace in code samples by @DerManoMann in #1034
• feat: openapi: 3.1.0 summary and description fields for refs by @bfanger in #1030
• OpenApi 3.1.0 updates for Licence by @DerManoMann in #1038
• Rationalise attribute parameters for types that inherit from Schema by @DerManoMann in #1037

Full Changelog: 4.0.5...4.1.0