cancelled quests should have message in party chat

[Alys]

When the quest owner or party leader cancels a quest that's still in the invitation phase, there's no indication for other party members that that's what happened and it can lead to confusion (there was a recent bug report from someone who understandably thought that something had gone wrong with the quest).

There should be a message posted to party chat to say, for example, "Alys cancelled the party quest Vice, Part 1: Free Yourself of the Dragon's Influence."

A similar message already exists for the case where a running quest is aborted so similar code could be used for this issue:

$ git grep "the party quest"
test/api/v3/integration/quests/POST-groups_groupid_quests_abort.test.js:130:    expect(Group.prototype.sendChat).to.be.calledWithMatch(/aborted the party quest Wail of the Whale.`/);
website/server/controllers/api-v3/quests.js:425:    const newChatMessage = group.sendChat(`\`${user.profile.name} aborted the party quest ${questName}.\``);
/code/habitica 2048 $ 

Also, as part of the fix for this issue, please change the comment shown below to remove (see questCancel for BEFORE) because the function it refers to is now called cancelQuest and it's likely that we'll forget to update the comment if we rename it again :)

habitica/website/server/controllers/api-v3/quests.js

Line 408 in a2261e3

// Abort a quest AFTER it has begun (see questCancel for BEFORE)

[HydeHunter2]

Hey!
I'd like to take this, if it's relevant.
Can I send a pull request?

[Alys]

@HydeHunter2 Thanks for the PR!

I've changed the labels on this issue to remove "help wanted".