v8.0 module release (#22975)

https://mattermost.atlassian.net/browse/MM-52079

```release-note
We upgrade the module version to 8.0. The new module path is github.com/mattermost-server/server/v8.
```


Co-authored-by: Doug Lauder <wiggin77@warpmail.net>

server/model/access.go

@@ -0,0 +1,72 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"net/http"
+)
+
+const (
+	AccessTokenGrantType  = "authorization_code"
+	AccessTokenType       = "bearer"
+	RefreshTokenGrantType = "refresh_token"
+)
+
+type AccessData struct {
+	ClientId     string `json:"client_id"`
+	UserId       string `json:"user_id"`
+	Token        string `json:"token"`
+	RefreshToken string `json:"refresh_token"`
+	RedirectUri  string `json:"redirect_uri"`
+	ExpiresAt    int64  `json:"expires_at"`
+	Scope        string `json:"scope"`
+}
+
+type AccessResponse struct {
+	AccessToken      string `json:"access_token"`
+	TokenType        string `json:"token_type"`
+	ExpiresInSeconds int32  `json:"expires_in"`
+	Scope            string `json:"scope"`
+	RefreshToken     string `json:"refresh_token"`
+	IdToken          string `json:"id_token"`
+}
+
+// IsValid validates the AccessData and returns an error if it isn't configured
+// correctly.
+func (ad *AccessData) IsValid() *AppError {
+	if ad.ClientId == "" || len(ad.ClientId) > 26 {
+		return NewAppError("AccessData.IsValid", "model.access.is_valid.client_id.app_error", nil, "", http.StatusBadRequest)
+	}
+
+	if ad.UserId == "" || len(ad.UserId) > 26 {
+		return NewAppError("AccessData.IsValid", "model.access.is_valid.user_id.app_error", nil, "", http.StatusBadRequest)
+	}
+
+	if len(ad.Token) != 26 {
+		return NewAppError("AccessData.IsValid", "model.access.is_valid.access_token.app_error", nil, "", http.StatusBadRequest)
+	}
+
+	if len(ad.RefreshToken) > 26 {
+		return NewAppError("AccessData.IsValid", "model.access.is_valid.refresh_token.app_error", nil, "", http.StatusBadRequest)
+	}
+
+	if ad.RedirectUri == "" || len(ad.RedirectUri) > 256 || !IsValidHTTPURL(ad.RedirectUri) {
+		return NewAppError("AccessData.IsValid", "model.access.is_valid.redirect_uri.app_error", nil, "", http.StatusBadRequest)
+	}
+
+	return nil
+}
+
+func (ad *AccessData) IsExpired() bool {
+
+	if ad.ExpiresAt <= 0 {
+		return false
+	}
+
+	if GetMillis() > ad.ExpiresAt {
+		return true
+	}
+
+	return false
+}