feat: warn about doc-endnote or doc-biblioentry on list items

The roles `doc-endnote` and `doc-biblioentry` are deprecated in ARIA 1.1, and authors should not use them on list items.

The HTML validator (validator.nu) raises an error when these roles are set on `li` elements.

This commit implements a more permissive approach for EPUBCheck:
- the roles are re-added the HTML schema
- we raise a warning (RSC-017) when the roles are present on `li` elements

src/main/resources/com/adobe/epubcheck/schema/30/epub-xhtml-30.sch

@@ -396,5 +396,14 @@
                     select="local-name(ancestor::$ancestor)"/> elements.</report>
         </rule>
     </pattern>
+
+    <pattern id="dpub-aria.doc-endnote.deprecated">
+        <rule context="h:li">
+            <report test="tokenize(@role,'\s+')='doc-endnote'"
+                >WARNING: The "doc-endnote" role should not be used on list item elements (deprecated in DPUB ARIA 1.1).</report>
+            <report test="tokenize(@role,'\s+')='doc-biblioentry'"
+                >WARNING: The "doc-biblioentry" role should not be used on list item elements (deprecated in DPUB ARIA 1.1).</report>
+        </rule>
+    </pattern>
 
 </schema>

src/main/resources/com/adobe/epubcheck/schema/30/mod/html5/block.rnc

@@ -101,6 +101,8 @@
 			|	common.attrs.aria.role.treeitem
 			|	common.attrs.aria.role.separator
 			|	common.attrs.aria.role.presentation
+			|	common.attrs.aria.role.doc-biblioentry
+			|	common.attrs.aria.role.doc-endnote
 			)?
 		)
 	li.inner =

src/test/resources/epub3/06-content-document/content-document-xhtml.feature

@@ -170,9 +170,12 @@ Feature: EPUB 3 — Content Documents — XHTML
     When checking document 'aria-roles-img-valid.xhtml'
     Then no errors or warnings are reported
 
-  Scenario: Verify the DPUB-ARIA roles allowed on `li`
-    When checking document 'aria-roles-li-valid.xhtml'
-    Then no errors or warnings are reported
+  Scenario: Report deprecated DPUB-ARIA roles on `li`
+    When checking document 'aria-roles-li-deprecated-warning.xhtml'
+    Then following warnings are reported:
+      | RSC-017 | "doc-endnote" role should not be used on list item |
+      | RSC-017 | "doc-biblioentry" role should not be used on list item |
+    Then no other errors or warnings are reported
 
   Scenario: Verify the DPUB-ARIA roles allowed on `nav`
     When checking document 'aria-roles-nav-valid.xhtml'