Adds the selection bar extension on Windows and Linux.

This is a fix for #9203.
Add context selection extension and enable the extensions on Mac.
Don't add Mac key bindings on other platforms.
Move the code so that we don't do the unnecessary replacement of `Ctrl` to `Cmd`.
Stop the older sidebar handling code from interfering with file tree
selection extension.
Merge pull request #9649 from adobe/rlim/startup-keymap-error

Don't add Mac key bindings on other platforms.
Don't show errors from user key map file when reloading without any extension
Merge pull request #9660 from adobe/rlim/no-error-on-reload

Don't show errors from user key map file when reloading without any extension
Merge pull request #9627 from adobe/dangoor/9203-selection-extension

Adds the selection bar extension in file tree
Use an unused shortcut for Reload without Extensions
Use default key map to restore the original key binding.
compare tagName in lowercase
Merge pull request #9672 from adobe/jeff/fix-9664

Blur Current Editor when focusing Pane W/O Editor the Focus from the Global Menu
Always clone the user key map regardless of whether it is empty or not.
Merge pull request #9663 from adobe/tom/reload-shortcut-2

Use an unused shortcut for Reload without Extensions
Merge pull request #9665 from adobe/rlim/restore-orig-bindings

Use default key map to restore the original key binding.
Merge branch 'master' into jeff/fix-9569