[DPE-3753] Support mongos tls

[MiaAltieri]

Issue

mongos charm does not support TLS and we want to re-use some of the shared libs owned by the mongodb chamr

Solution

update the shared lib owned by the mongodb charm so that mongos charm can easily support TLS

Future PRs:

1. add libs to mongos + add necessary changes to mongos src/charm
2. add sanity checks for mongos checking valid TLS configuration
3. Int tests