Add logtags support to filesystem module

If build_logtags is set to true, etc/event-log-tags will be built by
collecting all logtags files from all dependencies.

Note that this is different from Makefile's current behavior that
collects all logtags files, including ones from uninstalled modules. But
the behavior is probably unintended, and ideally each partition image
should have its own logtags, rather than putting all tags to /system.

Bug: 336189540
Test: m aosp_cf_system_x86_64
Change-Id: I72b384cbb65e812af909eacd18799bd86f1dab13