Everything now happens in main.ts, in the bootstrap family of
functions. The current flow is:
* check everything only on extension installation.
* if the user is on nightly channel, try to download the nightly
extension and reload.
* when we install nightly extension, we persist its release id, so
that we can check if the current release is different.
* if server binary was not downloaded by the current version of the
extension, redownload it (we persist the version of ext that
downloaded the server).
