* `DecryptionFailureTracker`: stronger typing
Use `DecryptionFailureCode` rather than string
* `DecryptionFailureTracker`: remove use of `DecryptionError`
The second argument to `MatrixEventEvent.Decrypted` callbacks is deprecatedf,
and we can get the info we need direct from the event. This means that we no
longer need to reference the internal `DecryptionError` class in the js-sdk.
* `DecryptionFailureTracker`: use a different Posthog code for historical UTDs
* Update for new UTD error codes
* Remove reference to private method
`MatrixEvent.setClearData` is private. Use the test helper instead.
* Remove redundant params to `expect.toBe`
* Convert to typescript
