Add Interactive Dialogs example

[hanzei]

This PR adds two examples for Interactive Dialogs:

• One dialog follows the example from the docs. Trigged via /dialog (https://docs.mattermost.com/developer/interactive-dialogs.html#example)
• One dialog contains no elements. Trigged via /dialog no-elements

On cancel a message is posted in the channel.

Fixes mattermost/mattermost#10286

[hanzei]

@jasonblais Please give this a first round of review.

[jasonblais]

Did a quick initial review. Looks good to me. Some minor proposed text adjustments

[hanzei]

@jasonblais Just to be clear: All the texts are Copy&Past from https://docs.mattermost.com/developer/interactive-dialogs.html#example. Should they also be updated in the docs?

[jasonblais]

@hanzei Yes, I made an update for three of the texts for docs mattermost/docs@8c6f83d

[jasonblais]

@hanzei Apart from text, is there anything else you'd like me to PM review?

[hanzei]

@jasonblais I update the command to show an help.

Apart from text, is there anything else you'd like me to PM review?

Basically: Is the dialog working as you thought it would? Might be a good time to check if Interactive Dialogs work as designed.
But nothing special to look at.

Please note that a message is shown in chat when you cancel the dialog.

[jasonblais]

@hanzei Would you be open to sharing a binary for demo plugin that I can use for testing?

[hanzei]

@jasonblais Sure. Will send your a DM.

[jasonblais]

This is looking great. Will make testing significantly easier.

1 - I received a JavaScript error when enabling the plugin you shared. May or may not be related to the changes on this PR.

2 - Would prefer there was an output posted which we already discussed in the GitHub issue. For now, we can just post an output of all the provided information except the email address.

3 - Propose including a reference in README, so that developers and QA are aware of this being available. Further details about interactive dialogs can be directed to https://docs.mattermost.com/developer/interactive-dialogs.html.

4 - Finally, a crash occurs with /dialog no-elements. This is expected until mattermost/mattermost-webapp#2726 is merged.

[hanzei]

1. I'm fairly confident that the errors are not related to this PR.
2. Fixed. The message now looks like this:
   
3. Sure, will do.
4. I'm fine with keeping this PR open, until MM-15128 - add support for interactive dialogs with no elements mattermost-webapp#2726 has been merged.

[mattermod]

This issue has been automatically labelled "stale" because it hasn't had recent activity.
A core team member will check in on the status of the PR to help with questions.
Thank you for your contribution!

/cc @jasonblais @hanzei

[jasonblais]

@hanzei That's okay for me if it's valuable to developers

[hanzei]

@jasonblais Moved the images to docs/dialog.md. Please take a second look.

[jasonblais]

Thanks Hanzei, just one text update proposal

[jasonblais]

Thanks @hanzei 👍

[hanzei]

cc @scottleedavis If you have feedback about this PR, feel free to share it.

[hanzei]

@levb @crspeller Gentle reminder to review this PR. Because it touches a lot of code, I would merge it rather sooner then later. Feel free to request a review from someone else, if you are to busy.

[crspeller]

Great to have an example of this.

[hanzei]

Switching to @ali-farooq0 as a reviewer because of the changed responsibilities.

[alifarooq0]

I see that you've added the example to https://docs.mattermost.com/developer/interactive-dialogs.html#example
are there any plans to update https://developers.mattermost.com/integrate/examples/ to include the interactive example there?

[hanzei]

are there any plans to update developers.mattermost.com/integrate/examples to include the interactive example there?

IMO the page is outdated and the list of integrations very selective. I would rather rework this whole page.