Add keyserverID to unencrypted notification and display to staff info about notification failure

Summary:
This differential:

1. Fixes recently introduced issue - notification was missing keyserverID after encryption failure.
2. Unifies encryption failure indicator field - keyserver used to put encryptionFailed while the NSE checked for encryptionFailure
3. Display additional error message notification to staff members if encryptionFailed key is present.

Test Plan:

1. Add throw in src/push/crypto.js.
2. Send notification to iOS device.
3. Ensure that two notifications are present: one correct and the other with encryption failure error message.

Reviewers: tomek, bartek, ashoat

Reviewed By: ashoat

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D12785