[AppStream] Adding install duration to <release> for firmware

[Richard Hughes]

Hi all,

I'm using AppStream metadata on the LVFS which is parsed by fwupd. So
far I've managed to use a subset of AppStream, and using the
per-component <custom> section for the crazy bits. I now need to add
the estimated install duration to the <release>. It's not
per-component as different releases may have very different
installation times (for instance, updating the EC v.s. updating the
EC+ME+BIOS) -- I've really got a few option here:

* Add some kind of duration to the specification that I can use in
<release> without feeling guilty
* Add a <X-install_duration> tag to <release>
* Add a new <custom> section to the <release>

For firmware, if we're installing an EC update on for instance an
XPS13, I *know* it's going to take 120 seconds +/- 5 seconds. That's
going to be true almost always. I'm not so sure this tag makes sense
for applications, as if we're installing a flatpak on a SSD with 16
core processor it might take 10 seconds, and the same flatpak on a
single-core ARM with spinning rust is going to take 5 minutes.

Happy for ideas here. Thanks.

Richard