test(HTML): add command tests for attributed p tags

- Add test cases for HTML to native, native to HTML, HTML to HTML,
  and HTML to HTML5 conversions
- Verify preservation of id, class, and data attributes on p tags

Author: Valgard

test/command/10768.md

@@ -0,0 +1,68 @@
+```
+% pandoc -f html -t native
+<p id="test" class="foo bar" data-custom="value">This is a paragraph with attributes.</p>
+^D
+[ Div
+    ( "test"
+    , [ "foo" , "bar" ]
+    , [ ( "wrapper" , "1" ) , ( "custom" , "value" ) ]
+    )
+    [ Para
+        [ Str "This"
+        , Space
+        , Str "is"
+        , Space
+        , Str "a"
+        , Space
+        , Str "paragraph"
+        , Space
+        , Str "with"
+        , Space
+        , Str "attributes."
+        ]
+    ]
+]
+```
+
+```
+% pandoc -f native -t html
+[ Div
+    ( "test"
+    , [ "foo" , "bar" ]
+    , [ ( "wrapper" , "1" ) , ( "custom" , "value" ) ]
+    )
+    [ Para
+        [ Str "This"
+        , Space
+        , Str "is"
+        , Space
+        , Str "a"
+        , Space
+        , Str "paragraph"
+        , Space
+        , Str "with"
+        , Space
+        , Str "attributes."
+        ]
+    ]
+]
+^D
+<p id="test" class="foo bar" data-custom="value">This is a paragraph
+with attributes.</p>
+```
+
+```
+% pandoc -f html -t html
+<p id="test" class="foo bar" data-custom="value">This is a paragraph with attributes.</p>
+^D
+<p id="test" class="foo bar" data-custom="value">This is a paragraph
+with attributes.</p>
+```
+
+```
+% pandoc -f html -t html5
+<p id="test" class="foo bar" data-custom="value">This is a paragraph with attributes.</p>
+^D
+<p id="test" class="foo bar" data-custom="value">This is a paragraph
+with attributes.</p>
+```