retrieveEncryptionSessionAsync 
suspend fun retrieveEncryptionSessionAsync(sessionId: String, useCache: Boolean = true, lookupProxyKey: Boolean = false, lookupGroupKey: Boolean = true): EncryptionSession
Retrieve an encryption session with the sessionId, and returns the associated EncryptionSession instance, with which you can then encrypt / decrypt multiple messages.
Return 
The retrieved EncryptionSession.
Parameters 
| sessionId | The ID of the session to retrieve. | 
| useCache | Whether or not to use the cache (if enabled globally). | 
| lookupProxyKey | Whether or not to try retrieving the session via a proxy. | 
| lookupGroupKey | Whether or not to try retrieving the session via a group. | 
Throws 
| SealdException |