Wrong text in for channel info messages

[Hocuri]

Info messages in channels use the group stock strings, e.g. "You changed the group name from X to Y". Instead, we should add four new stock strings in stock_str.rs:

    #[strum(props(fallback = "You changed the channel name from \"%1$s\" to \"%2$s\"."))]
    MsgYouChangedBroadcastName = 204,

    #[strum(props(fallback = "Channel name changed from \"%1$s\" to \"%2$s\" by %3$s."))]
    MsgBroadcastNameChangedBy = 205,

    #[strum(props(fallback = "You changed the channel image."))]
    MsgYouChangedBroadcastImg = 206,

    #[strum(props(fallback = "Channel image changed by %1$s."))]
    MsgBroadcastImgChangedBy = 207,

Then, document them in deltachat.h, and use them instead of their group equivalents.

[r10s]

i think, the "by" part is not really important here.

• the channel owner knows of course that they are the only one who can change that

• the channel subscriber might not even know the name of the owner, so the information that it was changed is sufficient. the owner name might be even confusing.

as a side effect, we have two strings less to translate.

strings would be (number should be picked as needed)

    #[strum(props(fallback = "Channel name changed from \"%1$s\" to \"%2$s\"."))]
    MsgBroadcastNameChanged = 205,

    #[strum(props(fallback = "Channel image changed."))]
    MsgBroadcastImgChanged = 207,

in some future, the "by" might be important, but that is then :)

[j-g00da]

Yes, I think this doesn't make much sense to create four variants for channels.