[branding] add Manjaro branding

src/branding/manjaro/branding.desc

src/branding/manjaro/languages.png

src/branding/manjaro/logo.png

src/branding/manjaro/show.qml

src/branding/manjaro/slide.png

src/branding/manjaro/slide2.png

src/branding/manjaro/slide3.png

src/branding/manjaro/slide4.png

src/branding/manjaro/slide5.png

src/branding/manjaro/squid.png