Replace manual types with generated types and cut a new tag for v1

[astromechza]

This PR proposes moving from the manual types to types generated from the json schema itself.

The schema is imported by a git subtree pull and converted into types by github.com/atombender/go-jsonschema

To avoid breaking compatibility with existing code, we cut a /v1 suffix (and assume the existing branch is v0).

This allows existing code to continue importing the "bare" type as github.com/score-spec/score-go while new code, or code upgraded to use this tag can use github.com/score-spec/score-go/v1.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• New chore (expected functionality to be implemented)

[delca85]

LGTM