IFW Installer QML type should have a writeFile method and ReadFile operation

Use case is to be able to write log files to capture the output of certain installer steps, like installing redistributable libs or running tests that check the installed software is
working.

There is the AppendFile operation, but operations apparently can't be used post-install, as they hang the installer process.

There is the AppendFile operation, but no ReadFile operation. So for example, to check the PATH defined in my .bashrc file and update it, I end up doing installer.readFile, followed by
installer.performOperation("AppendFile").

Documentation should mention, that installer.performOperation cannot be used for post-install operations.