fix: View expanded svg images from `<img>` tags to avoid js attacks

Description

Directly opening SVG images in the browser is a security issue. Hidden javascript can be executed. This PR opens SVG using a simple template with a single <img> tag. Other image types are directly sent to the browser.

The canonical URL action button does not open the file in a new browser tab any more for security considerations. Instead the canonical URL is copied to the user's clipboard:

Related resources

Checklist

[x] I have opened this pull request against master
[x] I have added or modified the tests when changing logic
[x] I have followed the conventional commits guidelines to add meaningful information into the changelog
[x] I have read the contribution guidelines and I have joined #workgroup-pr-review on Slack to find a “pr review buddy” who is going to review my pull request.

Codecov Report

All modified lines are covered by tests :white_check_mark:

Comparison is base (964f48d) 76.41% compared to head (3068e68) 76.43%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1429 +/- ## ========================================== + Coverage 76.41% 76.43% +0.02% ========================================== Files 75 75 Lines 3510 3514 +4 Branches 562 562 ========================================== + Hits 2682 2686 +4 Misses 666 666 Partials 162 162 ``` | [Files](https://app.codecov.io/gh/django-cms/django-filer/pull/1429?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=django-cms) | Coverage Δ | | |---|---|---| | [filer/\_\_init\_\_.py](https://app.codecov.io/gh/django-cms/django-filer/pull/1429?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=django-cms#diff-ZmlsZXIvX19pbml0X18ucHk=) | `100.00% <100.00%> (ø)` | | | [filer/admin/imageadmin.py](https://app.codecov.io/gh/django-cms/django-filer/pull/1429?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=django-cms#diff-ZmlsZXIvYWRtaW4vaW1hZ2VhZG1pbi5weQ==) | `90.38% <100.00%> (+0.80%)` | :arrow_up: |

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django-cms / django-filer