feat: add preference to customize global trackers

[subins2000]

What is the purpose of this pull request? (put an "X" next to item)

[ ] Documentation update
[ ] Bug fix
[x] New feature
[ ] Other, please explain:

What changes did you make? (Give an overview)

Added a new preference item, "Global Trackers". This list will be used as the default announceList instead of create-torrent module's list. This is done by setting the global variable WEBTORRENT_ANNOUNCE

Currently it requires a restart for the changes to apply. But I wonder if changes to WEBTORRENT_ANNOUNCE will reflect in app runtime after init ? 🤔

Tracker changes will apply on pause & resume of a torrent.

Which issue (if any) does this pull request address?

#881

Is there anything you'd like reviewers to focus on?

Does changes to WEBTORRENT_ANNOUNCE reflect in app runtime after init ? 🤔 My guess is that torrent needs to be paused and resumed for the new trackers to get applied ?

Changes to WEBTORRENT_ANNOUNCE will reflect to future webtorrent client.add calls. So pausing and resuming a torrent is enough.

[feross]

Rather than setting global.WEBTORRENT_ANNOUNCE, you can just pass in the announce option to the client.add or client.seed methods. That will add the specified trackers to the list of used trackers.

See: https://github.com/webtorrent/webtorrent/blob/2b8f65ab59422a70fe23d529bb9380d71e6cc2d8/lib/torrent.js#L262-L265

[subins2000]

In #881, I read

we're currently adding four default webtorrent (ws:// and wss://) trackers to all torrents without making this very clear to users. There is an argument to be made that we should allow users to turn this off (just from a privacy perspective)`

So change needs to be made to the global variable too, right ? That'd ensure user's choice to choose the tracker they want.

I'm now trying to avoid loading state in webtorrent.js and instead use IPC to pass the global trackers list. done in the next commits

[github-actions]

Is this still relevant? If so, what is blocking it? Is there anything you can do to help move it forward?

[subins2000]

Yes, this is still relevant. Ability to change the default trackers used is important, from a privacy perspective and user experience. Users have submitted duplicate issues since the creation of this PR asking this (#881).

[github-actions]

Is this still relevant? If so, what is blocking it? Is there anything you can do to help move it forward?

[DiegoRBaquero]

@subins2000 is this good to go?

[subins2000]

@DiegoRBaquero I just tested this locally again to confirm that it works. I see that using global.WEBTORRENT_ANNOUNCE or globalThis.WEBTORRENT_ANNOUNCE has the same effect but since the original was globalThis I changed to that in the last commit. All good to go!