Add Translation to DecryptionError in matrix-js-sdk/src/crypto

[mcalinghee]

We would like to add french translation on DecryptionError raised by matrix-js-sdk/src/crypto as they are directly displayed to users in tchap-web through TchapUnknownBody.tsx/UnknownBody.tsx

• We could add i18n facility in matrix-js-sdk (ie. matrix-react-sdk/src/languageHandler.tsx)
• Then we need to adapt the DecryptionError messages with i18n
  • In matrix-js-sdk/src/crypto/index.ts:
    • 'Unknown encryption algorithm "' + algorithm + '".'
  • In matrix-js-sdk/src/crypto/OlmDevice.ts:
    • adapt the method in calculateWithheldMessage to support i18n
  • In matrix-js-sdk/src/crypto/algorithms/megolm.ts:
    • "Missing fields in input"
    • "Unknown Error: Error is undefined"
    • " Trying to create a new secure channel and re-requesting the keys."
    • "The sender was unable to establish a secure channel."
    • "The secure channel with the sender was corrupted."
    • "The sender's device has not sent us the keys for this message."
    • "Message intended for room " + payload.room_id
  • In matrix-js-sdk/src/crypto/algorithms/olm.ts :
    • "Missing ciphertext"
    • "Not included in recipients"
    • "Bad Encrypted Message"
    • "Message was intented for " + payload.recipient
    • "Message not intended for this device"
    • "Message claimed to be from " + event.getSender()
    • "Message forwarded from " + payload.sender
    • "Message intended for room " + payload.room_id

[mcalinghee]

We can close this issue as a re-work of the DecryptionError has been done in element : matrix-org/matrix-react-sdk#9544.