Sometimes we want to surpress automatic scaling and converting
for dark theme. This adds a loadFromResource function with
additional flags which makes this possible.

Change-Id: I893cee82ad6942644755f0c5b772fb5f073bbf00
Reviewed-on: https://gerrit.libreoffice.org/30341Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>
Tested-by: Tomaž Vajngerl <quikee@gmail.com>