Update _pages.py - fix sorting for > 10 pages

[gothicVI]

Fix #2564

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[gothicVI]

@alexcjohnson @AnnMarieW
I've included the proposed change and added some test pages for

• >10 pages
• fractional ordering
• no order given

I hope these cover the changes well.

[AnnMarieW]

@gothicVI Thanks for posting about this issue on the forum and creating this pull request. It looks great!

@alexcjohnson regarding the question about id in the page_registry:

The id is not used in this test, but it is used in others in this folder.

Typically when assigning an id to components like buttons and links by looping through the dash.page_registry I like to use an id prop rather than using module. I think it makes the code more readable, and also if you change a file name in the pages folder it won’t break callbacks.

However, for tests, I think it would have been simpler - and better to just use the module. I could make a separate PR to refactor this if you like.

[alexcjohnson]

Thanks for the explanation of id @AnnMarieW - not a big deal, you're welcome to change it but it's not hurting anything.

[alexcjohnson]

💃 Thanks very much @gothicVI!