feat: remove receiver limit on .xdc size

[link2xt]

If we have downloaded the file anyway,
might as well allow to open it.

There is a corresponding discussion on the forum: https://support.delta.chat/t/proposal-remove-bump-xdc-file-size-cap/2828

[r10s]

i do not remember exactly: i think, the idea was that one cannot send too large webxdc by a modified client, to force ppl more into respecting the size limits

maybe okay to lift it, i am +/-0 here, one can still not sent them out easily

[Septias]

I think most developers are cautious enough to produce small webxdcs and having a limit does more harm than good. As @WofWca said in the forum, ported apps are very hard to get smaller without a huge amount of work as well as wasm-apps which include big binaries. It's fine for me to remove the limit.

[link2xt]

We can still enforce the limit on the apps added to xstore@testrun.org and maintain some quality standards there.

[link2xt]

one can still not sent them out easily

On forwarding the limit is currently not enforced by the way, I can forward large xdcs that I received already.

[r10s]

having a limit does more harm than good

good point. i agree that no strict limit is probably the better tradeoff, even more when thinking about webxdc in the broader term, not only about missing deduplication in dc (which is probably still not a huge issue, most images and all videos are larger than a webxdc and also forwarded)