Before this commit, setting:
```
$wgVectorConsolidateUserLinks = [
'logged_in' => true
];
```
would result in an orange talk notification that had missing or
incorrect attributes (`#ca-mytalk` instead of `#pt-mytalk` and missing
the `title` and `accesskey` attributes) when visiting modern Vector
with a talk notification visible. The notification's html looked like:
```
<li id="ca-mytalk" class="mw-echo-alert">
<a href="/wiki/User_talk:Newuser5">You have a new Talk page message</a>
</li>
```
The `pt-mytalk` id is important for echo to remove the notification [1].
The title and accesskey are important for accessibility reasons.
This commit corrects that by setting a `link-class`, setting an explicit
`id`, and NOT setting a `class` key. This results in html that is
correct in both modern and legacy Vector:
```
<li id="pt-mytalk">
<a href="/wiki/User_talk:Newuser5" class="mw-echo-alert" title="Your talk page [ctrl-option-n]" accesskey="n">You have a new Talk page message</a>
</li>
```
[1] 67bf58a489/modules/ext.echo.init.js (L172)
Bug: T274428
Change-Id: I5afc74992ad3153ac32df65ccf5fd03b469f05fb
7880cc1895