refactor(extractIcon): removed ubitmap and updated BGRABitmap submodule

[salvadorbs]

Small fix to solve the issue #143. More Windows & Linux testing required before porting the fix to development branch.

Todo:

• [x] Fix background icon
• [x] Test on Windows 10
• [x] Test on KDE Neon (QT5)
• [x] Test on Ubuntu (GTK2/GTK3)
• [x] Performance regression

[salvadorbs]

See https://github.com/bgrabitmap/bgrabitmap/issues/150