Add basic menubar
Add basic menubar

This includes a Developer menu that can be enabled or disabled through
the UI.

MaxiBoether/lbry-app,lbryio/lbry-electron,lbryio/lbry-app,lbryio/lbry-electron,lbryio/lbry-electron,jsigwart/lbry-app,jsigwart/lbry-app,MaxiBoether/lbry-app,jsigwart/lbry-app,akinwale/lbry-app,akinwale/lbry-app,akinwale/lbry-app,akinwale/lbry-app,lbryio/lbry-app,MaxiBoether/lbry-app,MaxiBoether/lbry-app,jsigwart/lbry-app