[New Feature] Custom SlavesFreeSound

[Flactine]

First check

• [X] The suggestion is NOT related to functionality of Ares, HAres, Kratos or any other YR engine extension.
• [X] The suggested feature / enhancement is NOT implemented in Ares/Phobos yet and the existing possibilites are not viable or good enough to achieve the wanted result.
• [X] I agree to elaborate the details if requested and provide thorough testing if the feature is implemented.
• [X] I added a very descriptive title to this issue.
• [X] I used the GitHub search and read the issue list to find a similar issue and didn't find it.
• [X] I thought out how the feature / enhancement should work and described it in the most detailed and clear way.

Description:

Now all kind of slaves use general setting "SlavesFreeSound= SlaveWorkerLiberated", so hope it can be custom for each type of slave.

Possible Implementation:

[SOMETECHNO]
CustomSlaveFreeSound=<none>        ; kind of voice