Allow adding book store entries by URL.

[ChristopherFritz]

The "Links" code is partially implemented but incomplete.

Detect the site based on the URL and store only the Unicode code(s) needed to reach the store page.
The interface for an added item shows the store name with a link that opens in a new tab/window. There must be a field to add extra text, such as b&w/color variants. It also needs to have whether it is physical or digital.

Example:

PHYSICAL:

Amazon:
https://www.amazon.co.jp/-/en/%E3%82%AA%E3%83%80-%E3%83%88%E3%83%A2%E3%83%92%E3%83%88/dp/4091273432/ref=tmm_other_meta_binding_swatch_0?_encoding=UTF8&qid=1666294059&sr=8-4
=> 4091273432

CDJapan:
https://www.cdjapan.co.jp/product/NEOBK-1985640
=> NEOBK-1985640

DIGITAL:

Amazon:
https://www.amazon.co.jp/-/en/%E3%82%AA%E3%83%80%E3%83%88%E3%83%A2%E3%83%92%E3%83%88-ebook/dp/B01M0RDBS5/ref=tmm_kin_swatch_0?_encoding=UTF8&qid=1666294059&sr=8-4
=> B01M0RDBS5

Rakuten:
https://books.rakuten.co.jp/rk/f4cb7008434635c897fd6961ba780060/
=> f4cb7008434635c897fd6961ba780060

Kobo:
https://www.kobo.com/jp/en/ebook/CHDL9EZDyDWX_WlhungAYA
=> CHDL9EZDyDWX_WlhungAYA

Bookwalker:
https://bookwalker.jp/defd946944-d78a-42e5-9759-f4dccdce74aa/
=> defd946944-d78a-42e5-9759-f4dccdce74aa