Rework parts of the content file engine handling especially when parsing the paths to get valid uri that can be used seemlessly with DocumentsContract. This fixes few issues with the content uri handling and allow more operations to be done without awkward workarounds: * The main issue was parsing the URI and creating a valid DocumentFile and parent if applicable, this was not handled quite properly before. So now, each case of a URI type is delt with separately (e.g. document, tree, mixed, children URIs) all while making sure to keep proper encoding while parsing the URI. * open() was getting involved into details like the path structure and not relying on DocumentFile implementation. * Handle file names, especially in cases where the file is not yet created and doing query() would fail, so in such cases initialize the DocumentFile with an initial name as fallback. * Moving operations were always failing due to the various name and path string manipulations, and not properly relying on the DocumentFile child/parent implementation. Pick-to: 6.10 6.9 6.8 Fixes: QTBUG-124011 Fixes: QTBUG-115143 Fixes: QTBUG-114979 Change-Id: I949f84fc658bf0588ebe239b07e6111d5b3b0cce Reviewed-by: Ville Voutilainen <ville.voutilainen@qt.io>