qmlls: generate and use response files in build folders

We currently have to pass a lot of options to qmlls (build folder, documentation paths, import paths) and it seems that this number of options won't stop increasing (like resources files as commented on https://codereview.qt-project.org/c/qt/qtdeclarative/+/609636, for example)

This makes the invocation of qmlls quite difficult and annoying for the qmlls client authors.

Suggestion: generate response files for qmlls in the build folder. CMake knows everything that qmlls needs to know, so it could write down a qmlls response file in the build folder. Then, the qmlls clients only need to call qmlls with the response file and don't need to care about the qmlls options (or at least the ones that are strictly build folder related, and that the user doesn't care about), like build folder path, import path, resource folder, and whatever we will need to add in the future.