fix: Add "sharedKeyEnc" to the metadata to propagate from server to client on receiving end

[sitaram-kalluri]

Resolves #1364

- What I did

• When running no-ports locally, an issue appear where the client waits for the srvd response and eventually times out. This occurs because the client receives the notification sent by srvd but fails to decrypt the message. The decryption fails because the "sharedEncryptedKey" received from the sender to the receiver is not being propagated from the receiver's server to the receiver's client via the notification.

Adding the log snippet:

SEVERE|2024-07-29 11:34:42.853820|NotificationServiceImpl (@alice🛠)|Failed to fetchData caused by
key not found : Exception: @alice🛠:shared_key@sitaram🛠 does not exist in keystore 

INFO|2024-07-29 11:34:44.149909| SrvdChannel |Still waiting for srvd response 
INFO|2024-07-29 11:49:03.865867| SrvdChannel |Still waiting for srvd response 
WARNING|2024-07-29 11:49:04.976872| SrvdChannel |Timed out waiting for srvd response 

Error : TimeoutException: Connection timeout to srvd @sitaram🛠 service

- How I did it

• Add "sharedEncKey" to the metadata in MonitorVerbHandler.dart

- How to verify it

• After the changes, tested no-ports manually and able to run successfully. Adding the log file.
  client-no-ports.log

- Description for the changelog

• In MonitorVerbHandler, add "sharedKeyEnc" to the metadata to propagate the sharedEncryptedKey in
  notifications from the server to the client.

There is a follow-up PR in at_client.

[gkc]

LGTM. Note that there was an old ticket for this - #1364