WebViewUpdateService.dumpState: print a line for each WebView package

Whenever there is a bug related to the WebView package configuration it
is difficult to tell from the WebViewUpdateService dumpsys message
whether the webview package configuration xml file is wrong, or whether
we haven't installed the correct WebView package. If a package doesn't
show up in the dumpstate log it could either be uninstalled or not be
part of the configuration at all.

This CL ensures all packages from the configuration file are printed in
the dumpsys statement - especially the ones that are not installed on
the device.

Bug: 65532751
Test: manual: 'dumpsys webviewupdate' to ensure non-installed WebView
packages are printed.

Change-Id: I15bf9b2813e6ade43ed7fb093f111891c26f33d3