Show Running Extensions in a grid

<!-- ⚠️⚠️ Do Not Delete This! feature_request_template ⚠️⚠️ --> <!-- Please read our Rules of Conduct: https://opensource.microsoft.com/codeofconduct/ --> <!-- Please search existing issues to avoid creating duplicates. --> <!-- Describe the feature you'd like. --> # Summary of current experience The current Show Running Extensions experience lays out a list of running extensions similar to how it is laid out for extensions shown in the side bar. There is left and right-aligned text as well as secondary information for certain extensions. Actions in the top-right include Run code, Save extension host profile (disabled until profiling is finished), Debug extension host, and Start extension host profile.  After you start and then stop the extension host profile, the profile time populates in the list underneath the activation time and the save profile icon is enabled. The saving and viewing experience includes a few steps. The default extension the file is saved as is “.cpuprofile.txt”. If you want to open the file in VS Code to inspect after you save the file, you have to manually change the extension to “.cpuprofile” and open it in VS Code. Once the file is opened, you can click on the flame view which opens up an additional file that has the same name as the original file opened. # Idea https://user-images.githubusercontent.com/60596156/133375380-e05a2a07-1df6-439c-aa44-f4077ded8b24.mov A proposed change is that we could display the running extensions in a grid. The icons in the top-right corner have also been changed. Debug extension host is using the debug icon rather than the green triangle icon to better differentiate from the Run code icon. I also made a small tweak to the Start extension host profile icon for visual consistency and weight across the icons. There is also no save profile icon because once the profiling is finished, an untitled file…