MinervaTemplate::getTemplateData sets data that is indirectly setting data already set in SkinMinerva.
For example SkinMinerva::prepareBanners sets the `banners`field.
All these keys should be set inside SkinMinerva::getTemplateData.
For example the banners key could be set by making prepareBanners return a string and updating SkinMinerva::getTemplateData like so:
```
'banners' => $this->prepareBanners(),
```
All remaining code inside MinervaTemplate is in the scope of this task:
```
'banners' => $data['banners'],
'isAnon' => $data['username'] === null,
'userNotificationsHTML' => $data['userNotificationsHTML'] ?? '',
'data-main-menu' => $this->getMainMenuData( $data ),
'hasheadingholder' => $hasHeadingHolder,
'taglinehtml' => $data['taglinehtml'],
'headinghtml' => $data['headinghtml'] ?? '',
'postheadinghtml' => $data['postheadinghtml'] ?? '',
'userMenuHTML' => $data['userMenuHTML'],
```
# TODO
[x] At the end of this task MinervaTemplate should cease to exist.
[x] When handling `isAnon` make sure the data field is replaced with the existing is-anon field rather than creating a new one.
[x] There should be no calls to $tpl->set inside SkinMinerva
[x] There should be no creation of MinervaTemplate inside SkinMinerva
=== QA steps
- Make sure an article page in Minerva looks the same between beta cluster and production
- Test for anonymous users
- Test for logged in users with AMC disabled
- Test for logged in users with AMC enabled