[lib] update currentAsOf for SIWE auth

Summary:
Updating this to have correct [type](https://github.com/CommE2E/comm/blob/4737cce6f2e643073bfe27ab42f8cc7bab12593f/lib/types/message-types.js#L647).

This partially caused [ENG-5883](https://linear.app/comm/issue/ENG-5883/rahul-sees-socket-crash-loop-due-to-policy-acceptance-issue).
We were returning `0` as the default value for `currentAsOf` in here: [link](https://github.com/CommE2E/comm/blob/371f6f808e5e8c44fb4b175081b0b1624225ff55/lib/selectors/keyserver-selectors.js#L57).
This later caused a condition from D9965 truthy right after login.

Test Plan:
1. Log `currentAsOf`
2. Log in using SIWE
3. Make sure it has correct type and value (previously it was number, not object).

Reviewers: inka, tomek, michal, ashoat

Reviewed By: ashoat

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D10058

lib/actions/siwe-actions.js

@@ -72,7 +72,7 @@ const siweAuth =
         messageInfos: response.rawMessageInfos,
         truncationStatus: response.truncationStatuses,
         watchedIDsAtRequestTime: watchedIDs,
-        currentAsOf: response.serverTime,
+        currentAsOf: { [ashoatKeyserverID]: response.serverTime },
       },
       userInfos,
       updatesCurrentAsOf: response.serverTime,