Document --utility-user-dynamic-privileges server option

As the result of fix for PS-7127 we added new server option

 utility-user-dynamic-privileges

It works similarly to already existing

utility_user_privileges 

but allows user to specify dynamic privileges for Utility User

https://dev.mysql.com/doc/refman/8.0/en/privileges-provided.html

As dynamic privileges can be registered/unregistered in runtime (can be defined in plugins for example) it is not possible to list possible values. The main reason we added it is possibility to give the UU SYSTEM_USER privilege (but it is not limited to this privilege)

Documentation should look like:

Option utility_user_dynamic_privileges allows a comma-separated list of extra access dynamic privileges to grant to the utility user.

Example: --utility-user-dynamic-privileges =”SYSTEM_USER,AUDIT_ADMIN”