custom-editor: fix closing dirty custom text editor issue

[safisa]

What it does

Fix the issue: Closing a dirty/modified custom editor based on CustomTextEditorProvider doesn't ask the user to save, it just saves it on close (#11592)

How to test

1. use the cat scratch custom editor extension example from vscode (you can download it from this issue custom-editor: restore editor as part of layout #10787)
2. open the example.cscratch file
3. do some changes in the custom editor UI (add some cats by clicking on the scratch button)
4. close the dirty tab, you need to see the popup asking to save the file.

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

[vince-fugnitto]

Thank you for your contribution 👍

In order to accept your changes please be sure to sure to sign the eclipse contributor agreement (eca) with the same email as your authorship.

[safisa]

In order to accept your changes please be sure to sure to sign the eclipse contributor agreement (eca) with the same email as your authorship.

I already signed it.
It is my first PR to Theia, do I need to do anything else?
Thanks in advance

[vince-fugnitto]

I already signed it. It is my first PR to Theia, do I need to do anything else? Thanks in advance

@safisa just the ECA for the moment, I verified and there does not seem to be a valid one registered yet (for [email protected]):

[safisa]

I used my private email: [email protected]
This email is also linked to my Github account, but it is not set as my primary email address!

[vince-fugnitto]

I used my private email: [email protected] This email is also linked to my Github account.

@safisa in order for the ECA check to actually pass you'll need to use the same email in both your authorship and ECA.
At the moment there is a mismatch:

From 02ec66c106d900818ff3ed9e92e0422c2f4522b9 Mon Sep 17 00:00:00 2001
From: Safi <[email protected]>
Date: Mon, 22 Aug 2022 14:52:53 +0300
Subject: [PATCH 1/2] This will fix the issue: Closing a dirty/modified custom
 editor based on CustomTextEditorProvider doesn't ask the user to save, it
 just save it on close https://github.com/eclipse-theia/theia/issues/11592
...

[safisa]

Hi @vince-fugnitto @msujew
Can you review this PR?

[vince-fugnitto]

I confirmed that the changes work well 👍

• if a custom-editor is dirty, closing the editor triggers the prompt
• save from the prompt will save the editor
• cancel will close the dialog
• don't save will revert the changes and close the editor

[safisa]

Hi @vince-fugnitto
This PR is already approved, is it going to be merged before the next Theia version?

[vince-fugnitto]

@safisa it should, I just wanted to give others a chance to review.
Do you mind removing the changelog entry since it is in the wrong release? (I'll re-add it when I perform the release at the end of the month).