Only call /user in GitHub auth extension if we don't have account information

[TylerLeonhardt]

/user can take around 100ms... running that for every token even in parallel can last upwards to a half a second. Let's call /user only when needed.

[TylerLeonhardt]

fixed in 37a8fe9

[TylerLeonhardt]

verification:

• With VS Code insiders
• Make sure you're logged in to a few GitHub extensions
• Open the GitHub Authentication Output channel
• You shouldn't see anything in the log that talks about "Verified session with the following scopes:" or "filling in account information"

If you really wanna test this you can see if any requests to /user (the github API) were requested.

[alexr00]

Verified that none of the logs showed up.