Enable encryption in MXRealmCryptoStore

[manuroe]

For extra security, we want to encrypt the DB used by MXCrypto.

[ismailgulek]

We experienced below error when we tried to encrypt crypto DB. Seems like we cannot use encrypted Realms across the app and NSE targets.

[MXRealmCryptoStore] realmForUser gets error: Error Domain=io.realm Code=1 "/private/var/mobile/Containers/Shared/AppGroup/5F1819A3-A507-44A0-AB33-2131CF9E2BFF/MXRealmCryptoStore/@ismailgulekmac3:matrix.org-ciphered.realm: Encrypted interprocess sharing is currently unsupported.DB has been opened by pid: 431. Current pid is 430." UserInfo={NSLocalizedDescription=/private/var/mobile/Containers/Shared/AppGroup/5F1819A3-A507-44A0-AB33-2131CF9E2BFF/MXRealmCryptoStore/@ismailgulekmac3:matrix.org-ciphered.realm: Encrypted interprocess sharing is currently unsupported.DB has been opened by pid: 431. Current pid is 430., Error Code=1}