Added ability to overwrite managers in Update User

Updated Update User API (/update-user-1) to accept a new optional boolean parameter overwriteManagerEmails, which will overwrite the user's list of managers with what gets passed into managerEmails parameter if set to true. managerEmails should be passed in as an array.

Also updated descriptions of all parameters to indicate optional fields.

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Note: If managerEmails is an empty array and this new boolean is set to true - the result will be removing all managers for that user, as the manager list will be empty.

Note: If managerEmails is an empty array and this new boolean is set to true - the result will be removing all managers for that user, as the manager list will be empty.

Note: If `managerEmails` is an empty array and this new boolean is set to true - the result will be removing all managers for that user, as the manager list will be empty.