Import/Export front-end

Let's use this bug to move forward the work of the Import/Export tool.
The objective is to have this ready and polished for 102, a bit of a tight timeline but we can do it.
The work will follow the mock-ups published here: https://app.presentator.io/#/xz3hqwc5

Implementation strategy

PART 1

• [ ] Remove the sidebar
• [ ] Implement the new User Interface with colors based on variables.css file
• [ ] Guarantee a guided, wizard like, experience during the import
• [ ] Don't use any subdialog, html dialog, or regular dialog, for any step

PART 2

• [ ] Implement the "Wizard steps" at the top of the page
  • The steps will dynamically change to reflect the users' selection
  • The steps are not clickable to enforce the CONTINUE/BACK navigation

PART 3

• [ ] Redirect specific entry points to the related steps of the import tab
  • Import Events and Tasks shows directly Import from a File => Import Calendar File step
  • Import Address Book shows directly Import from a File => Import Address Book File step

PART 4 (Can be delayed after 102)

• [ ] Make the whole area a droppable container for supported files
• [ ] If a valid file is dropped, show the correct screen step to allow users confirming the data importing

Import from a File screen

This screen is different in the mock-up from what we currently have, as we directly show options to import Calendar or Address Book.
The Import from a File screen should show 3 options:

• Import a back-ed up profile (zip) (triggers the file picker on "Continue")
• Import calendars
• Import address books

These screens should show the options we currently have.

Some screens are missing in the mock-up, so let me know if you need any further design or overview.

Pushed by mkmelin@iki.fi:
https://hg.mozilla.org/comm-central/rev/5c7610e673f3
Update about:import flow start to use wizard instead of tabs. r=aleca

Depends on D146440

Depends on D146441

Depends on D146442

Pushed by geoff@darktrojan.net:
https://hg.mozilla.org/comm-central/rev/ab1c0d4cf027
Inline import progress and add summary page. r=aleca
https://hg.mozilla.org/comm-central/rev/e0774107077f
Add missing elements to import flow. r=aleca
https://hg.mozilla.org/comm-central/rev/6c91d618129c
Add all the copy to the import flow. r=aleca
https://hg.mozilla.org/comm-central/rev/55b24e7f2f07
Update import flow styles. r=aleca

There's a test failure in comm/mail/test/static/browser_parsable_css.js from https://searchfox.org/comm-central/rev/510ad49d89eba24e69ff7809e2f75483125fe7a4/mail/themes/shared/mail/aboutImport.css#58

Pushed by mkmelin@iki.fi:
https://hg.mozilla.org/comm-central/rev/74a4091d1c27
Fix invalid CSS in import details grid. r=mkmelin

For export, Tab name/label is showing as import.

(In reply to Jaise from comment #11)

For export, Tab name/label is showing as import.

On the latest daily it shows me the correct tab title, "Export".

(In reply to Jaise from comment #11)

For export, Tab name/label is showing as import.

Thank you for the screenshot. Based on that this is a build before all the patches that just landed above. It's possible that daily isn't quite in the update channel yet, sorry for saying "latest daily" when I should've said "build from the latest comm-central".

Pushed by mkmelin@iki.fi:
https://hg.mozilla.org/comm-central/rev/b914c584f5e5
Persist export tabs across restarts. r=mkmelin

Pushed by mkmelin@iki.fi:
https://hg.mozilla.org/comm-central/rev/b27e62d1624f
Add steps on top of import wizard. r=aleca

This is considered complete for 102.