qmlls: do not run qqmljsimportvisitor twice

Currently, qmlls runs qqmljsimportvisitor twice: once during the DOM construction and once in the module that does the linting (qqmllintsuggestions.cpp).

Maybe it could be changed to not rerun the qqmljsimportvisitor a second time during the linting and to reuse the qqmljsscope created during the DOM construction.