Add advanced targeting for desktop users with 0 pinned tabs (#12960)

Because

- We need to be able to target users who currently have 0 pinned tabs in
their open windows. See [bugzilla
1971552](https://bugzilla.mozilla.org/show_bug.cgi?id=1971552)

This commit

- Adds targeting to only include `!hasPinnedTab` for desktop users.   

Fixes #12959

---------

Co-authored-by: Jared Lockhart <[email protected]>
Co-authored-by: dataops-ci-bot <[email protected]>
Co-authored-by: Yashika Khurana <[email protected]>
Co-authored-by: Benjamin Forehand Jr <[email protected]>
Co-authored-by: Daniel Thorn <[email protected]>

Author: 6 people

experimenter/experimenter/targeting/constants.py

@@ -2771,6 +2771,17 @@ def __post_init__(self):
     application_choice_names=(Application.DESKTOP.name,),
 )
 
+NO_PINNED_TABS = NimbusTargetingConfig(
+    name="Users who have no pinned tabs",
+    slug="no_pinned_tabs_desktop",
+    description=("Targets users who have 0 pinned tabs in their open windows."),
+    targeting=("!hasPinnedTabs"),
+    desktop_telemetry="",
+    sticky_required=False,
+    is_first_run_required=False,
+    application_choice_names=(Application.DESKTOP.name,),
+)
+
 NON_SIDEBAR_USERS = NimbusTargetingConfig(
     name="Users that have never used the sidebar",
     slug="non_sidebar_users",