Add support for secrets on windows

[andrewjensen]

Overview

This adds support for getting and setting secrets on Windows.

We're delegating to the cross-keychain package for the low-level interactions on Windows. Why?

• I'm less familiar with the Windows ecosystem so I want to delegate to a battle-tested library rather than roll our own implementation
  • I originally looked at keytar and @github/keytar, but they are both in maintenance mode
• I'm choosing to not change the MacOS and Linux implementation over to cross-keychain to avoid making a breaking change.
  • In the future, we could do some clever migration logic like we're doing with handleTemporaryBaseUrlMigration.

The change has forced some core functions in secrets.ts and runtime.ts to become async, which impacts all the commands. So the diff for this change is broad but shallow. There is no change to the existing user experience for MacOS and Linux. In those cases, we're only switching from the blocking execaSync function to the async execa function, but the user is waiting for the same work to complete either way.

Screenshot of dx init