Implement GET /users/email/{email} endpoint for APIv4 (#5309)

* added get user by email endpoint for APIv4

* added get user by email endpoint unit test and driver

* removed the appended return of user ids on logout

* Added RequireEmail to validate user email. Also updated the get user by email endpoint and unit test

model/client4.go

@@ -56,6 +56,10 @@ func (c *Client4) GetUserRoute(userId string) string {
 	return fmt.Sprintf(c.GetUsersRoute()+"/%v", userId)
 }
 
+func (c *Client4) GetUserByEmailRoute(email string) string {
+	return fmt.Sprintf(c.GetUsersRoute()+"/email/%v", email)
+}
+
 func (c *Client4) GetTeamsRoute() string {
 	return fmt.Sprintf("/teams")
 }
@@ -210,6 +214,16 @@ func (c *Client4) GetUser(userId, etag string) (*User, *Response) {
 	}
 }
 
+// GetUserByEmail returns a user based on the provided user email string.
+func (c *Client4) GetUserByEmail(email, etag string) (*User, *Response) {
+	if r, err := c.DoApiGet(c.GetUserByEmailRoute(email), etag); err != nil {
+		return nil, &Response{StatusCode: r.StatusCode, Error: err}
+	} else {
+		defer closeBody(r)
+		return UserFromJson(r.Body), BuildResponse(r)
+	}
+}
+
 // GetUsers returns a page of users on the system. Page counting starts at 0.
 func (c *Client4) GetUsers(page int, perPage int, etag string) ([]*User, *Response) {
 	query := fmt.Sprintf("?page=%v&per_page=%v", page, perPage)