release: 3.9.1

chore: Remove pages/update.css

feat(vscode): update to version 1.53.2

Before this commit, if the tests fail then the artifacts don't get uploaded.
This makes it harder to debug failing e2e tests.

To prevent this, this commit adds an "if" condition which says always run this
step.

Source: https://stackoverflow.com/a/58859404/3015595

It appears the associated HTML for these styles was removed in
554b6d6f

docs(README, ci): add docs shield with link to version docs

With this the extension host is working again.

They now are all prepended with VSCODE_. Also added the parent pid to
ensure it shuts down when the parent dies.

It doesn't mean much until we persist terminals though, I think.

fix(ci): add step to remove docker images on linux-arm64 

This adds a step to remove the docker images and hopefully free up space in the
linux-arm64 part of ci.

This adds a step to remove both the release packages and the test artifacts as
a step at the end of test in ci.yaml.

This makes it accessible via keyboard.

The theme callback would set innerHTML on the header which wipes out the
dismiss button. With an inner div we can replace the inner HTML without
worrying about other elements in the header.

Closes #2799.

This is preventing my ripgrep from searching vscode.

Closes #2742.

feat(testing): add unit tests for register