[remote] Prefer to open a file in an existing window even when that window is connected to a remote with that file opened

<!-- ⚠️⚠️ Do Not Delete This! bug_report_template ⚠️⚠️ --> <!-- Please read our Rules of Conduct: https://opensource.microsoft.com/codeofconduct/ --> <!-- 🕮 Read our guide about submitting issues: https://github.com/microsoft/vscode/wiki/Submitting-Bugs-and-Suggestions --> <!-- 🔎 Search existing issues to avoid creating duplicates. --> <!-- 🧪 Test using the latest Insiders build to see if your issue has already been fixed: https://code.visualstudio.com/insiders/ --> <!-- 💡 Instead of creating your report here, use 'Report Issue' from the 'Help' menu in VS Code to pre-fill useful information. --> <!-- 🔧 Launch with `code --disable-extensions` to check. --> Does this issue occur when all extensions are disabled?: Yes <!-- 🪓 If you answered No above, use 'Help: Start Extension Bisect' from Command Palette to try to identify the cause. --> <!-- 📣 Issues caused by an extension need to be reported directly to the extension publisher. The 'Help > Report Issue' dialog can assist with this. -->  You open a project that has a .devcontainer folder, and vscode asks you to "reopen in devcontainer", so you open the devcontainer. You now have one vscode window of a project in a devcontainer. Reproducing: - You navigate to another application, such as file explorer or GitHub desktop and find a file in the project you're working on, which exists in the devcontainer. - You right click on the file, and you can choose an option in windows explorer to "Open with code" or in GitHub desktop "open in Visual Studio Code". It doesn't matter which option you take, you click the menu item. (I reckon it would also be an issue for just generally opening filetypes that have code as the default opener) Behaviour: vscode will now open this file in a brand new vscode window, outside of the devcontainer. We think the preferred behaviour should be for vscode to detect that this file th…