webCommandMetadata object is contained inside a commandMetadata one, so it is
not accessible from the root of the navigationEndpoint object.
The corresponding statement has been moved at the bottom of the specific
endpoints parsing, as the webCommandMetadata object is present almost
everywhere, otherwise URLs of some endpoints would have be changed, such as
uploader URLs (from channel IDs to handles).
As no ParsingException is now thrown by getUrlFromNavigationEndpoint, and so by
getTextFromObject, getUrlFromObject and getTextAtKey, the methods which were
catching ParsingExceptions thrown by these methods had to be updated.
URLs got in the HTML version of getTextFromObject are now escaped properly to
provide valid HTML to clients. This has been also done for attribute
descriptions, with the description text for this type of descriptions.
As YouTube descriptions are in HTML format (except for the fallback on the JSON
player response, which is plain text and only happens when there is no visual
metadata or a breaking change), all URLs returned are escaped, so tests which
are testing presence of URLs with escaped characters had to be updated (it was
only the case for YoutubeStreamExtractorDefaultTest.DescriptionTestUnboxing).