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

api4/params.go

@@ -25,6 +25,7 @@ type ApiParams struct {
 	CommandId string
 	HookId    string
 	EmojiId   string
+	Email     string
 	Page      int
 	PerPage   int
 }
@@ -66,6 +67,10 @@ func ApiParamsFromRequest(r *http.Request) *ApiParams {
 		params.EmojiId = val
 	}
 
+	if val, ok := props["email"]; ok {
+		params.Email = val
+	}
+
 	if val, err := strconv.Atoi(r.URL.Query().Get("page")); err != nil {
 		params.Page = PAGE_DEFAULT
 	} else {