[lib] Fix keyserver not present in keyserver store error

Summary:
issue: https://linear.app/comm/issue/ENG-5905/uncaught-typeerror-cannot-read-properties-of-undefined-reading
The following error was showing up on some peoples consoles:

Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'updatesCurrentAsOf')
    at U7 (prod.4ff39ebc9fcd.build.js:2:4648139)
    at prod.4ff39ebc9fcd.build.js:2:4683479
    at prod.4ff39ebc9fcd.build.js:2:4682129
    at y (prod.4ff39ebc9fcd.build.js:2:1767761)
    at prod.4ff39ebc9fcd.build.js:2:4683981
    at Object.dispatch (prod.4ff39ebc9fcd.build.js:2:2405643)
    at WebSocket.<anonymous> (prod.4ff39ebc9fcd.build.js:2:4669607)

The reason was that setNewSessionActionType was being dispatched from the Socket without keyserverID in payload. The keyserver id is required, but dispatch is not typed very well, so flow didn't catch it. This was causing a new keyserver to be added to the keyserver store by the keyserver reducer - a keyserver with id undefined. This keyserver was not previously present in the store, so state.keyserverStore.keyserverInfos[keyserverID].updatesCurrentAsOf in baseReducer would throw.
So the fist thing that has to be done, is fixing the payload.
Secondly, we have an action that can add a keyserver to the store, and this would also result in this error being thrown. But when addKeyserverActionType is dispatched we don't need to update currentAsOf or updatesCurrentAsOf, so we will just if this out (change in master-reducer.js line 87)
Thirdly, we should protect ourselfes from this error in case someone adds some code that can add a keyserver and doesn't update this code (change in master-reducer.js line 109).

Test Plan:

1. Tested that the setNewSessionActionType action with broken payload indeed causes this error to show up, by dispatching it manually
2. Tested that adding the keyserverID to the payload fixes the issue, and the error does not appear (before changes to baseReducer)
3. Tested that the code is not executed when addKeyserverActionType is dispatched
4. Tested that even if a new keyserver is added by setNewSessionActionType with broken payload, the error is not thrown

Reviewers: ashoat, kamil, tomek

Reviewed By: kamil, tomek

Differential Revision: https://phab.comm.dev/D10091