Add support for list-template and list-empty widgets for specifying list widget templates (#7784)

Cherry picked from #7710

editions/test/tiddlers/tests/data/list-widget/WithExplicitTemplatesOverriddenByAttributes.tid

@@ -0,0 +1,33 @@
+title: ListWidget/WithExplicitTemplatesOverriddenByAttributes
+description: List widget with explicit templates
+type: text/vnd.tiddlywiki-multiple
+tags: [[$:/tags/wiki-test-spec]]
+
++
+title: Output
+
+\whitespace trim
+
+\procedure test(filter)
+<$list filter=<<filter>> emptyMessage="Zero" template="Template">
+	<$list-template>
+		<$text text=<<currentTiddler>>/>
+	</$list-template>
+	<$list-empty>
+		None!
+	</$list-empty>
+</$list>
+\end
+
+<<test "1 2 3">>
+
+<<test "">>
+
++
+title: Template
+
+<$text text=<<currentTiddler>>/><$text text=<<currentTiddler>>/>
++
+title: ExpectedResult
+
+<p>112233</p><p>Zero</p>