Expose User tasks and all task commands in vscode Web

<!-- ⚠️⚠️ 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. --> - VS Code Version: Web - OS Version: any There are many task commands that are not available in the web version such as `Open User Tasks` based on the context key `SHOW_TASKS_COMMANDS_CONTEXT` defined in `src/vs/workbench/contrib/tasks/browser/task.contribution.ts`, which relies on support for shell and process tasks, while these commands can be useful for custom execution tasks. Is it also possible to expose global tasks to extensions such as extension provides a task that is shared across any workspace. In our use case, the tasks users would like to run would remain consistent across any workspace so an extension being able to define and save a task in the global `tasks.json` would be hugely beneficial. In the extension API the task constructor does take a scope parameter but as per the comment on it doesn't seem supported. ` * @param scope Specifies the task's scope. It is either a global or a workspace task or a task for a specific workspace folder. Global tasks are curre…