Add support for preload="metadata"

[suzmas]

Would like to display audio duration without needing to download entire file - native audio accepts preload="metadata" (docs).

Wondering if there's any plan to support this option in the future / if it would be considered?

[borodadada]

Yes, need preload!!!

[etaybarzilay89]

I need preload="metadata" as well.

We don't want to load many audio files in advanced but do want to show their duration.

[etaybarzilay89]

@suzmas I saw someone made a PR for this feature request:
#1140