Cleanup: comments in struct declarations

Use a consistent style for declaring the names of struct members
in their declarations. Note that this convention was already used in
many places but not everywhere.

Remove spaces around the text (matching commented arguments) with
the advantage that the the spell checking utility skips these terms.
Making it possible to extract & validate these comments automatically.

Also use struct names for `bAnimChannelType` & `bConstraintTypeInfo`
which were using brief descriptions.

source/blender/editors/include/ED_file_indexer.h

@@ -131,7 +131,7 @@ void ED_file_indexer_entries_clear(FileIndexerEntries *indexer_entries);
  */
 void ED_file_indexer_entries_extend_from_datablock_infos(
     FileIndexerEntries *indexer_entries,
-    const LinkNode * /* BLODataBlockInfo */ datablock_infos,
+    const LinkNode * /*BLODataBlockInfo*/ datablock_infos,
     int idcode);
 
 #ifdef __cplusplus