zimcheck: report all links in error in HTML files

[benoit74]

While checking internal and external links in HTML items (at least), zimcheck reports only one error per ZIM entry:

zim-tools/src/zimcheck/checks.cpp

Line 446 in 3ad99a1

break;

and

zim-tools/src/zimcheck/checks.cpp

Line 459 in 3ad99a1

break;

While this probably makes sense from a perspective where one wants no error at all, it also make it more complex to have an oversight of all issues in a given ZIM (we have to fix first error, run zimcheck again, potentially multiple time until we've exhausted all errors).

It also makes it hard to cope with "acceptable" errors which might hide real issue. This is my case with a zimit ZIM where the error reported on all items is an error about a missing JS resources which has been blocked by browsertrix addblocker. This first error is "acceptable" in the sense that ZIM still works pretty well from a user perspective. However on the specific ZIM I'm diagnosing, there are few (or many, I don't know) other errors which are "not acceptable": missing HTML pages making navigation broken. I can't use zimcheck to find these errors.

I would like to have an option like "report all" which allows to report all errors on all HTML items in a given ZIM.