feat: refactor api spec to use OpenAPI and add missing spec

Convert the existing swagger2.0 file to a moden OpenAPI file.
Add missing endpoitns and model definitions.

Signed-off-by: Lucas Roesler <roesler.lucas@gmail.com>

gateway/vendor/github.com/go-ozzo/ozzo-validation/v4/required.go

@@ -0,0 +1,74 @@
+// Copyright 2016 Qiang Xue. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package validation
+
+var (
+	// ErrRequired is the error that returns when a value is required.
+	ErrRequired = NewError("validation_required", "cannot be blank")
+	// ErrNilOrNotEmpty is the error that returns when a value is not nil and is empty.
+	ErrNilOrNotEmpty = NewError("validation_nil_or_not_empty_required", "cannot be blank")
+)
+
+// Required is a validation rule that checks if a value is not empty.
+// A value is considered not empty if
+// - integer, float: not zero
+// - bool: true
+// - string, array, slice, map: len() > 0
+// - interface, pointer: not nil and the referenced value is not empty
+// - any other types
+var Required = RequiredRule{skipNil: false, condition: true}
+
+// NilOrNotEmpty checks if a value is a nil pointer or a value that is not empty.
+// NilOrNotEmpty differs from Required in that it treats a nil pointer as valid.
+var NilOrNotEmpty = RequiredRule{skipNil: true, condition: true}
+
+// RequiredRule is a rule that checks if a value is not empty.
+type RequiredRule struct {
+	condition bool
+	skipNil   bool
+	err       Error
+}
+
+// Validate checks if the given value is valid or not.
+func (r RequiredRule) Validate(value interface{}) error {
+	if r.condition {
+		value, isNil := Indirect(value)
+		if r.skipNil && !isNil && IsEmpty(value) || !r.skipNil && (isNil || IsEmpty(value)) {
+			if r.err != nil {
+				return r.err
+			}
+			if r.skipNil {
+				return ErrNilOrNotEmpty
+			}
+			return ErrRequired
+		}
+	}
+	return nil
+}
+
+// When sets the condition that determines if the validation should be performed.
+func (r RequiredRule) When(condition bool) RequiredRule {
+	r.condition = condition
+	return r
+}
+
+// Error sets the error message for the rule.
+func (r RequiredRule) Error(message string) RequiredRule {
+	if r.err == nil {
+		if r.skipNil {
+			r.err = ErrNilOrNotEmpty
+		} else {
+			r.err = ErrRequired
+		}
+	}
+	r.err = r.err.SetMessage(message)
+	return r
+}
+
+// ErrorObject sets the error struct for the rule.
+func (r RequiredRule) ErrorObject(err Error) RequiredRule {
+	r.err = err
+	return r
+}