gnu: Rename qtbase to qtbase-5.

This change was automated via the following command:

$ git ls-files | xargs sed -i 's/,qtbase)/,qtbase-5)/g'
$ git ls-files | xargs sed -i 's/inherit qtbase)/inherit qtbase-5)/g'
$ git ls-files | xargs sed -i 's/package-version qtbase)/package-version qtbase-5)/g'
$ git checkout etc    # to clear some spurious changes

This is done so the qtbase package can be upgraded to version 6 in the
following commit.

gnu/packages/documentation.scm

@@ -330,7 +330,7 @@ local system.")
       (inputs
        `(("libarchive" ,libarchive)
          ("sqlite" ,sqlite)
-         ("qtbase" ,qtbase)
+         ("qtbase" ,qtbase-5)
          ("qtdeclarative" ,qtdeclarative)
          ("qtwebchannel" ,qtwebchannel)
          ("qtwebengine" ,qtwebengine)