Bulk Editing: Add selection state to products list

[ealeksandrov]

Part of: #8517

Description

This PR adds bulk editing state on Products List.
It replaces navbar content, disables pull-to-refresh, switches table view into multiple selection mode.

Testing

1. Build and run the app in debug/alpha mode.
2. On the products list tap the "Bulk Edit" button in the navbar.
3. Confirm navbar title changes, all buttons are replaced with "Cancel".
4. Confirm pull-to-refresh is unavailable.
5. Select a few products from the list.
6. Confirm title changes, displaying amount of selected items.
7. Tap "Cancel" in navbar.
8. Confirm normal navbar title and items are back, pull-to-refresh is enabled.

Video

Simulator.Screen.Recording.mp4

---

• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[wpmobilebot]

You can test the changes from this Pull Request by:

• Clicking here or scanning the QR code below to access App Center
• Then installing the build number pr8563-09db3ad on your iPhone

If you need access to App Center, please ask a maintainer to add you.

[Ecarrion]

I'm not sure if we can use tableView.indexPathsForSelectedRows safely. When the table view reloads due to a page being loaded this property gets cleaned.

issue-with-selection.mov

I think we will have to change how we update the table view with new pages or we will have to store these selections on a view model.

What do you think?

[ealeksandrov]

Good catch! Added ProductsListViewModel to store selection state.

[Ecarrion]

Looks good! I just found one strange glitch where the cell separators disappear if you start selecting from the top of the list.

Feel free to create an issue for it!

[ealeksandrov]

Thanks! Created #8608