[4.x] Fixes

[jasonvarga]

• Fix set picker not appearing in live preview. Closes [4.x] Replicator-Set-Picker and Dropdown can not be opened in live preview #7900
• Fix empty time fieldtype causing an error
• Fix global site selector icon
• Allow click propagation, fixes [4.x] Filter doesn't close automatically #7898
• Adjust draggability in assets fieldtype. Fixes Unable to remove image from assets fieldtype [4.0] #7878
• Tweak the asset fieldtype drag ui.
• Add a z-index to the main div to fix elements appearing over the global search overlay. Fixes [4.x] Global Search has a tiny z-index problem #7908

[what-the-diff]

PR Summary

• Fix z-index of global header
  Adjust the header layering to ensure proper visibility
• Add missing light icon for site selector
  Include a previously missing icon for better user experience
• Remove unnecessary clickaway from filters popover (fixes Implement Asset Container creation command #5)
  Improve filter interaction by eliminating unneeded click behavior
• Fix time fieldtype masking issue with 0 values (Extension file generation commands default to the App directory #6)
  Resolve a problem displaying time values correctly, especially with 0 values