[FEATURE] Ability to specify custom validation schemas for Traefik v3

[peterbuga]

Is there an existing issue for this?

• I have searched the existing issues

Feature description

Traefik v3 introduced, changed and deprecated an array config options that make them incompatible with current schemas.

Ability to specify custom .json schemas would greatly improve this tool and make it work in the feature.

Anything else?

traefik-config-validator/pkg/validation/validation.go

Line 30 in e6d2341

TraefikJsonSchemaRef = "https://raw.githubusercontent.com/SchemaStore/schemastore/master/src/schemas/json/traefik-v2.json"