Add `_alias.dictionary_uri` to aliases where possible

[vaitkus]

The DDLm reference dictionary defines the _alias.dictionary_uri attribute, however, it does not seem to be widely used in the CIF_CORE or any other of the IUCr dictionaries. This information would be useful since it would allow to more easily track down the origin of a specific alias and to double check if the definitions in different dictionaries haven't diverted too much. However, the semantics of _alias.dictionary_uri currently seem a bit unclear to me so it would be great to resolve that first (see issue #481).

Also, there were some discussions in PR #479 of adding the URI to deprecated items. I will prepare a separate draft PR and link it to this issue.

[vaitkus]

PR #483 introduces the _alias.dictionary_uri values for deprecated aliases. The URIs were chosen to refer to the versions of the dictionary in which those specific aliases were deprecated. These URIs might need to be changed if the definition of the _alias.dictionary_uri attribute get reworded