Bug 1784192 - part 9: Rename TypeInState to PendingStyles r=m_kato

Additionally,
* `PropItem` -> `PendingStyle`
* `StyleCache` -> `PendingStyleCache`
* `AutoStyleCacheArray` -> `AutoPendingStyleCacheArray`

And finally, `PendingStyle` (formally `PropItem`) is changed to `class` and
its members are encapsuled.

Differential Revision: https://phabricator.services.mozilla.com/D155318

editor/libeditor/HTMLEditorDataTransfer.cpp

@@ -14,8 +14,8 @@
 #include "HTMLEditHelpers.h"
 #include "HTMLEditUtils.h"
 #include "InternetCiter.h"
+#include "PendingStyles.h"
 #include "SelectionState.h"
-#include "TypeInState.h"
 #include "WSRunObject.h"
 
 #include "mozilla/dom/Comment.h"