pull in PWB Code Server upstream changes and use Positron product name

[sharon-wang]

• addresses #5282
• cherry-picks the commit from #5293, to apply the upstream fixes to positron main
  • this also brings in a fix for https://github.com/rstudio/rstudio-workbench-vscode-ext/issues/269
• related to https://github.com/posit-dev/positron/issues/5267

Description from #5293:

Pulls in changes from https://github.com/rstudio/vscode-server/pull/142 and updates the product name to be Positron-specific.

This will allow the Workbench team to cleanly implement the RPCs necessary to save session state between user logouts.

QA Notes

Some work will still need to be done on the Workbench side. See https://github.com/rstudio/rstudio-pro/issues/6820 The Workbench team will need to retest the VS Code state work and rework those existing tests to work with Positron.

[sharon-wang]

I didn't see an obvious way to test this

I think we'll be able to test this in Positron on Workbench once the additional state management pieces are in. We could check for Positron session state being persisted while logged into a Workbench session (with https://github.com/posit-dev/positron/issues/5267 in mind) and Positron session state cleared on logout. I'm not sure we can easily verify this change outside of Workbench though.

The Workbench extension updates will be verified as part of https://github.com/rstudio/rstudio-workbench-vscode-ext/issues/269. We can verify that an updated version of the Workbench extension (version 1.5.16) is now bundled with reh-web Positron.