ui: Rename streams to channels in user-facing strings

[Khader-1]

Fixes: #630

[rajveermalviya]

Thanks, This looks good to me :)

Updating l10n data labels & template variables can be done later, as mentioned in #630 (comment)

[gnprice]

Thanks @rajveermalviya for the first review!

When advancing a review to the next stage, let's be sure to ping on the thread the next reviewer, as well as update the labels, to help make sure everyone's on the same page. So @kenclary over to you 🙂

(And please also take a look in your inbox for the invite I've sent for this repo; that'll let you update labels and reviewers in turn, but as a side effect it'll also make it possible to name you in the GitHub "request review" feature, because it'll make GitHub aware that you're connected to this org/repo.)

[kenclary]

I love a straightforward PR.

[chrisbobbe]

Thanks @Khader-1! Some small comments on the commit sequence:

Here are the commits in this revision:

3437549 intl: Use channel instead of stream
1227390 ui: Rename stream to channel in user-facing strings
b407423 notif: Rename stream to channel in displayed notifications

The first and second commits are both about changing strings that appear in the in-app UI, which at this point means all the UI except notifications. So I think it would be fine to squash them into one commit, with a summary line like:

ui: Rename stream to channel in user-facing strings, except notifications 

(If you don't want to squash them together, then each commit should have some more words about exactly which strings are being treated. Basically the second commit is about the in-app strings that are still TODOs for #277.)

I think it would also be fine to squash the notifications-strings commit into that as well (i.e., squashing your revision's three commits into one), and have the commit message say that all user-facing strings are treated in the commit. That's still in line with our convention that a commit represents one coherent idea.

[Khader-1]

Thanks @chrisbobbe! A new revision with a single commit PTAL.

[chrisbobbe]

Great, LGTM! Marking for Greg's review now.

[gnprice]

Thanks all! Looks good — merging.

I'll add a second commit on top, to update the Japanese translation. 🙂 (That's a small partial translation, which we have just for the sake of end-to-end testing that our i18n setup within the app works, pending #276 which will let us take translation contributions broadly like we do for other Zulip codebases.)

FTR, the searches I did to confirm the rename was complete were:

$ git grep -i '".*stream'
$ git grep -i \''.*stream'

Most of the results were in test/ or in generated *.g.dart files for deserializing the Zulip server API; I looked through the rest and confirmed they were also either in the API, in a comment, or otherwise not user-facing.

Looking forward to seeing most of those — and matches for git grep -i stream more generally — go away as part of #631! That will be a bigger task: definitely many commits, and probably best as several PRs, to keep each PR down to a convenient size for review.