gnu: qtdeclarative: Rename to qtdeclarative-5.

Automated via the following commands:

  git grep -l '\bqtdeclarative\b' | xargs sed -E 's/qtdeclarative/\0-5/g' -i
  git checkout NEWS

gnu/packages/image-viewers.scm

@@ -519,7 +519,7 @@ It supports JPEG, PNG and GIF formats.")
      (list pkg-config qttools))
     (inputs
      (list qtbase-5
-           qtdeclarative
+           qtdeclarative-5
            qtsvg-5
            boost
            eigen
@@ -532,7 +532,7 @@ It supports JPEG, PNG and GIF formats.")
            lcms
            openexr-2
            qtwebengine
-           qtdeclarative
+           qtdeclarative-5
            qtwebchannel
            fftwf
            gsl