Preferences: Add preferences kind and remove unused navbar settings (#59621)

kinds/preferences/preferences_kind.cue

@@ -0,0 +1,36 @@
+package kind
+
+name:     "Preferences"
+maturity: "merged"
+
+lineage: seqs: [
+	{
+		schemas: [
+			{
+				// UID for the home dashboard
+				homeDashboardUID?: string
+
+				// The timezone selection
+				// TODO: this should use the timezone defined in common
+				timezone?: string
+
+				// day of the week (sunday, monday, etc)
+				weekStart?: string
+
+				// light, dark, empty is default
+				theme?: string
+
+				// Selected language (beta)
+				language?: string
+
+				// Explore query history preferences
+				queryHistory?: #QueryHistoryPreference
+
+				#QueryHistoryPreference: {
+								// one of: '' | 'query' | 'starred';
+								homeTab?: string
+				} @cuetsy(kind="interface") //0.0
+			},
+		]
+	},
+]