feat: use FileSystemFileHandle to modify a file on the local filesystem

[josxha]

Launch Checklist

• Briefly describe the changes in this PR.
• Link to related issues.
• Include before/after visuals or gifs if this PR includes visual changes.
• Write tests for all new functionality.
• Add an entry to CHANGELOG.md under the ## main section.

Changes

• This pull request makes use of the FileSystemFileHandle API to modify a local file. No need to download it - just click save.
• I don't know how to cover this functionality by tests so I need directions in case test coverage is required.
• The pull request adds @types/wicg-file-system-access as a new dev dependency which I am not really pleased about but can't think of a way around it.

Known Limitations

• The used File API is only available in when accessed from https or on localhost.
• There is no visual indicator that the file has been saved. Previously the browser showed it as a new download.

Issue

• Use the File System Access API to edit a local style #964

Screenshots

Menu

Open modal

Save modal

[HarelM]

Yes, I believe there is a need to cover this in tests although I struggled with Cypress and file open button.
Can you add a video with the new behavior?

[josxha]

Yes, I believe there is a need to cover this in tests although I struggled with Cypress and file open button.

The this pull request removes the html input element. I found a way to test with it but it would require to somehow mock the File System Access API and I can't find a solution for this.

Can you add a video with the new behavior?

maputnik-showcase1.mp4

[HarelM]

Overall this looks like a great improvement, I'm happy to see that file API finally made it to the browsers...

[HarelM]

Let me know if you managed to find a way to test this...

[josxha]

From my pr description:

I don't know how to cover this functionality by tests so I need directions in case test coverage is required.

I didn't break any tests with this pr, so the functionality hasn't been covered previously. I'd write some tests to cover it but will need some guidance.

[HarelM]

I can't find anything when using Google about Cypress and this new API.
If you find anything let me know, if not then I'll merge as is...

[josxha]

If you find anything let me know, if not then I'll merge as is...

I looked into it but couldn't find a way with Cypress tests, too. Maybe another test setup for unit tests would be beneficial?

I changed "Download HTML" to "Create HTML" to be more in line. From my point of view the pr is ready to get merged. (:

[HarelM]

Thanks!
Should be published in a few minutes.