New rendering: simplify the source link

[romu70]

⚠️ If your issue is about an error during fetching a link, please read: http://doc.wallabag.org/en/user/errors_during_fetching.html#how-can-i-help-to-fix-that

Issue details

Instead of showing a part of the URL which is always variable in length and so can disturb the display of the metadata, show "Source" as link title.

Environment

• wallabag version (or git revision) that exhibits the issue:
• How did you install wallabag? Via git clone or by downloading the package?
• Last wallabag version that did not exhibit the issue (if applicable):
• php version:
• OS:
• type of hosting (shared or dedicated):
• which storage system you choose at install (SQLite, MySQL/MariaDB or PostgreSQL):

Steps to reproduce/test case

Please provide necessary steps for reproduction of this issue, or better the
reduced test case (without any external dependencies, if possible).