Support restore_pinned_tabs_on_demand

[TobiaszCudnik]

Short description

When saving a session with discarded (suspended) tabs, which are also pinned, the extension should store that information and then apply when restoring. Related issue on auto-tab-discard.

Steps to reproduce

1. Start browser with clean profile
2. Install Tab Session Manager
3. Install auto-tab-discard
4. Set browser.sessionstore.restore_pinned_tabs_on_demand to true in about:config
5. Pin some tabs
6. Discard them
7. Save the session
8. Restore the session in an empty window

Expected result

Tabs are loaded in the same state as before (discarded).

Actual result

All the tabs are being fully loaded.

Platform information

• Platform (OS): Mac
• Version of browser: 99.0.1
• Version of Tab Session Manager: 6.11.1

Thanks!