Make the clock agenda's calendars and row count configurable

The agenda part filtered calendars through the search settings and always
collapsed after four rows. It now has its own selection: an exclusion set
(`clockWidgetCalendarPartExcludedCalendars`, empty = all) that is added to the
search settings' exclusions, because the picker only offers calendars those
settings leave enabled.

The row cap is `clockWidgetCalendarPartMaxRows` (1..8, default 4); the agenda
shows that many events and then a "+N more events" row if more are left, so
with the default five events now render as four rows plus "+1 more event"
instead of three plus "+2".

Both are configured in `ConfigureCalendarPart`, shown by the clock sheet while
the Events part is enabled: a slider, a Calendars row that expands into a
colour-tinted checkbox per calendar, and a button to Settings -> Search ->
Calendar (new `ROUTE_SEARCH_CALENDARS`) for calendars the search settings
disable. A missing calendar permission shows a banner with a Grant button.

New setting fields default to the previous behaviour, so no datastore
migration is needed.

core/i18n/src/main/res/values/strings.xml

@@ -615,6 +615,12 @@
     <string name="preference_clockwidget_alarm_part_summary">Show alarms that will ring within the next 24 hours</string>
     <string name="preference_clockwidget_calendar_part">Events</string>
     <string name="preference_clockwidget_calendar_part_summary">Show today\'s agenda</string>
+    <string name="preference_clockwidget_calendar_part_events">Visible events</string>
+    <string name="preference_clockwidget_calendar_part_calendars">Calendars</string>
+    <string name="preference_clockwidget_calendar_part_all_calendars">All calendars</string>
+    <string name="preference_clockwidget_calendar_part_calendars_summary">%1$d of %2$d calendars</string>
+    <string name="preference_clockwidget_calendar_part_no_calendars">No calendars found</string>
+    <string name="preference_clockwidget_calendar_part_manage_calendars">Manage calendars</string>
     <string name="clockwidget_calendar_part_all_day">all-day</string>
     <plurals name="clockwidget_calendar_part_more_events">
         <item quantity="one">+%d more event</item>

core/preferences/src/main/java/de/mm20/launcher2/preferences/LauncherSettingsData.kt

@@ -59,6 +59,8 @@ data class LauncherSettingsData internal constructor(
     val clockWidgetMusicPart: Boolean = true,
     val clockWidgetDatePart: Boolean = true,
     val clockWidgetCalendarPart: Boolean = false,
+    val clockWidgetCalendarPartExcludedCalendars: Set<String> = emptySet(),
+    val clockWidgetCalendarPartMaxRows: Int = 4,
     val clockWidgetDynamicZoneSlots: Int = 1,
     val clockWidgetFillHeight: Boolean = false,
     val clockWidgetAlignment: ClockWidgetAlignment = ClockWidgetAlignment.Bottom,

core/preferences/src/main/java/de/mm20/launcher2/preferences/ui/ClockWidgetSettings.kt

@@ -11,6 +11,10 @@ import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.flow.map
 
+/** Bounds for the number of event rows the agenda shows before collapsing. */
+const val MinCalendarPartRows = 1
+const val MaxCalendarPartRows = 8
+
 data class ClockWidgetParts(
     val date: Boolean,
     val music: Boolean = false,
@@ -61,6 +65,39 @@ class ClockWidgetSettings internal constructor(
         }
     }
 
+    /**
+     * Calendars the agenda does not show. Empty means "all calendars".
+     */
+    val calendarPartExcludedCalendars
+        get() = launcherDataStore.data.map { it.clockWidgetCalendarPartExcludedCalendars }
+            .distinctUntilChanged()
+
+    fun setCalendarExcluded(calendarId: String, excluded: Boolean) {
+        launcherDataStore.update {
+            it.copy(
+                clockWidgetCalendarPartExcludedCalendars =
+                    if (excluded) it.clockWidgetCalendarPartExcludedCalendars + calendarId
+                    else it.clockWidgetCalendarPartExcludedCalendars - calendarId
+            )
+        }
+    }
+
+    /**
+     * Number of event rows in the agenda before it collapses into a "+N more events" row.
+     */
+    val calendarPartMaxRows
+        get() = launcherDataStore.data
+            .map { it.clockWidgetCalendarPartMaxRows.coerceIn(MinCalendarPartRows, MaxCalendarPartRows) }
+            .distinctUntilChanged()
+
+    fun setCalendarPartMaxRows(rows: Int) {
+        launcherDataStore.update {
+            it.copy(
+                clockWidgetCalendarPartMaxRows = rows.coerceIn(MinCalendarPartRows, MaxCalendarPartRows)
+            )
+        }
+    }
+
     fun setDatePart(datePart: Boolean) {
         launcherDataStore.update {
             it.copy(clockWidgetDatePart = datePart)