* Add supported timezones into config
Remove Timezone list creation in favor of timezone from configs
Add Timezone field to Users table
Clean up format of SupportedTimezones in config
* Remove unwanted change
* Add test for updating user timezone
* Add empty map[string]string if Timezone is null
* Add EnableTimezoneSelection config
* Revert back to map[string]string for ClientConfig
* Refactor SupportedTimezones into timezones.json
* Include timezones.json in TestConfigFlag
* Add timezone api endpoint
* Bump varchar size to 256 and setMaxSize in user_store
* Refactor LoadConfig to LoadConfig and LoadTimezoneConfig
* Remove unnecessary argument in LoadConfig, mail_test
* Add test for timezone endpoint
* Add license header
* Refactor timezones endpoint to system.go
* Add system base route to timezone endpoint
* db timezone upgrade in db v4.9
* Avoid saving SupportedTimezones to config.json
* Add timezonePath support in config
* Remove EnableTimezoneSelection from config
* Use return statement without return parameter
* Refactor test for SupportedTimezones
* Check for supportedTimezone != nil instead of using len
* Decouple SupportedTimezones out of Config
* Fix failing test
* Add LastTeamIconUpdate back in upgrade.go
* Write timezone config in config_flag_test
* Add code fallback for default timezone support
