ViewPageTarget: Refactor 'replace' tabLayout

The 'add' tabLayout path is pretty basic and up to date. The
older (now active again) tabLayout 'replace' was fairly outdated
and unmaintained.

Fixes:
* Attributes copied from the original (except for the 'id'
  attribute) were not actually beinged copied over because they
  don't exist on the ca-edit list item, but on the anchor link
  inside that list item.
* Clean up messages from the module registry that were unused.
  Keys 'accesskey-ca-edit' and 'tooltip-ca-edit' were also inexistant.
* Add message keys for tooltip and accesskey of editsource tab.

Depends on I0bde1a228983c58b in mediawiki/core.

Bug: 47396
Change-Id: If598552fac639da645a8b1273c5fc6028695fcc1
Merge "ViewPageTarget: Refactor 'replace' tabLayout"