This exports FuSecurityAttrs into libfwupdplugin so that we can pass the plugins
this object rather than a 'bare' GPtrArray. This greatly simplifies the object
ownership, and also allows us to check the object type before adding.
In the future we could also check for duplicate appstream IDs or missing
properties at insertion time.
This change also changes the fu_plugin_add_security_attrs() to not return an
error. This forces the plugin to handle the error, storing the failure in the
attribute itself.
Only the plugin know if a missing file it needs to read indicates a runtime
problem or a simple failure to obtain a specific HSI level.
If the measurements are missing but it's a UEFI system, it's a good indication
that the user has secure boot turned off.
Notify the user on the UEFI device through a non-fatal `UpdateMessage`
To accomplish this, move fu-uefi-vars into the plugin library for other plugins to use
We don't actually need either of the things it provides (looking up in source
and built, and converting to an absolute path) so just replace it with
g_build_filename() instead.
This also has the advantage that it does the right thing on Windows.
