fix: Restore send as external message when payload is big

[atomrc]

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This will make sure that sending a large message to many devices will not generate a huge payload to encrypt and send to backend.

In this case, an external message is sent (basically there is 1 encrypted payload and each client only gets a encrypted decryption key for that huge payload)

This feature was killed when the non-qualified message sending abilities were sunset (see https://github.com/wireapp/wire-web-packages/pull/4927). This PR ports back the external message feature back to the fully qualified message sending.

[sonarqubecloud[bot]]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

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