Add persistent id to API info

[malberts]

Closes #34

• Uses a hook to add values to the core Actions Info API.
• Works with other result formats
• Can be used to retrieve multiple pages
• Adds nothing when an invalid page is specified
• Adds id or null for valid pages

API request: /api.php?action=query&prop=info&titles=Main Page|Page|Does Not Exist|Foo

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Future low priority improvement:

• fetch persistent ids in bulk

[malberts]

Draft to check if this approach makes sense.

[waximabbax]

How can I generate an ID for page 1?

I ran

and also putting

{{#ppid:}}

[malberts]

How can I generate an ID for page 1?

Which version of MW are you using there? That warning there might require you to run the maintenance script differently. But that branch is still WIP, so there's also a possibility that something is wrong with it in a later version of MW.

Otherwise, just change the API to look for a page you created yourself: /api.php?action=query&prop=info&titles=Some Page

{{#ppid:}}

That only displays the ID in the page. It won't generate it.

[waximabbax]

Works for me now.