Create a structure `OfficeWorker` having the following public fields:
-`name` as `String`.
-`age` as `u32`.
-`role` as `WorkerRole`.
Create an enum `WorkerRole` which can be `Admin`, `User` or `Guest`.
Implement for both the trait `From<&str>`. For `OfficeWorker` the string will have the format `"name,age,role"`, for `WorkerRole` the format of the string will be the `"role"` name in lower case.