Empty MRU- back button does nothing

[roblourens]

Testing microsoft/vscode-jupyter#11963

• Open a new window where no kernels have been used
• Open the kernel picker, get the kernel source picker
• Click the back button
• The quick pick flashes closed/opened and shows the source picker again

[minsa110]

Was trying the MRU out with my new machine and ran into the same thing. Just adding a few more comments:

• The progress bar makes it look like the process to find kernels just hangs
• I'd expect to see Install suggested extensions like the old experience
• Select **Another** Kernel feels unfinished--it's my first time picking a kernel for this project so I expect it to tell me to just Select a Kernel