Support RegisterValidationCtx()

[jonas0616]

In validator.v10, apart from using RegisterValidation() to register validator.Func, it could also use RegisterValidationCtx() to register validator.FuncCtx. This enables you to validate parameters using an additional context.Context that is passed in.

However, this does not yet enable passing gin.Context to validator.FuncCtx. When validating the parameters, it is necessary to replace validator.Validate.Struct() with validator.Validate.StructCtx() and pass down *gin.Context.