Impement web share target api

[pwFoo]

Web share target api allows tinode to register to systems share dialog e.g. to share a link from browser to a tinode chat.

https://developer.mozilla.org/en-US/docs/Web/Manifest/share_target

Works fine with Twitter Pinafore for Mastodon Web Apps.

[or-else]

1.5 years later and it's still not widely supported. I installed X (twitter) on Mac M1/Chrome and it does not appear in the Share... menu. Is this feature being actually used by any webapp?