Optimize asset library for file saves

When using a really large project like https://bugreports.qt.io/browse/QDS-7181 with 6000 files then saving a file starts to take up to 10 secodns on my machine.

Most of the time is spend in:

 connect(&m_assetCompressionTimer, &QTimer::timeout, this, [this]() {

m_assetsModel->refresh();

in assetslibrarywidget.cpp

The content folder contains around 6000 files in this case.

We need to optimize this.

One option is to use changedDirPath from connect(m_fileSystemWatcher, &Utils::FileSystemWatcher::directoryChanged, [this](const QString & changedDirPath).

A quick hack would be to block the m_assetCompressionTimer while we save a file.