Implement parsing of the <icon> element in OPDS 1.x feeds

[x0000ff]

The OPDS 1.x is based on Atom, and Atom’s Feed may contain an icon tag. I found it useful to parse the <icon> tag.

1.1. Introduction
The Open Publication Distribution System (OPDS) Catalog format is a syndication format for electronic publications based on Atom [RFC4287] and HTTP [RFC2616].

atom:feed elements MUST NOT contain more than one atom:icon element.

• ✅ Tests are updated

[mickael-menu]

Thank you, this is a useful parsing addition.

Instead of adding a new property in the OpdsMetadata model, could you add the icon as a Link object in the Feed.links collection? This is how we handle external resources in our models.

You can add an icon LinkRelation in the Link object to mark it as the feed icon.

[x0000ff]

Thank you, this is a useful parsing addition.

Instead of adding a new property in the OpdsMetadata model, could you add the icon as a Link object in the Feed.links collection? This is how we handle external resources in our models.

You can add an icon LinkRelation in the Link object to mark it as the feed icon.

Thank you, @mickael-menu!

I've update the PR. Could you check?

[mickael-menu]

Thank you for making the changes @x0000ff! However, I can't merge it because it is not up to date with develop. Could you upgrade the branch or better yet, enable "edit from maintainers"? (see https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/allowing-changes-to-a-pull-request-branch-created-from-a-fork#enabling-repository-maintainer-permissions-on-existing-pull-requests).

In your other PR as well #655

[x0000ff]

Thanks a lot, @mickael-menu! I did both ✅