[update] update to upstream commit c83365b
Squashed 'qttools/' changes from 9209274..c152d93

c152d93 use designercomponents-private correctly
d403785 Add changes-5.1.0 file
9631fd4 Find the cmake version template in the install location.
8da32f8 Assistant: Adding 'qtquickcontrolsstyles' to the list of qch loaded.

git-subtree-dir: qttools
git-subtree-split: c152d9339f4fcee22e4ec17404ceb39794284f75
Merge commit '631f8aa42b5b84281e4632238e3309a4b4d871e3'