Prevent user from changing his permissions and status

[dominik-zeglen]

I want to merge this change because it prevents the user from harming himself :) Also adds pretty avatars.
Resolves #2966

Pull Request Checklist

1. Privileged views and APIs are guarded by proper permission checks.
2. All visible strings are translated with proper context.
3. All data-formatting is locale-aware (dates, numbers, and so on).
4. Database queries are optimized and the number of queries is constant.
5. Database migration files are up to date.
6. The changes are tested.
7. The code is documented (docstrings, project documentation).
8. GraphQL schema and type definitions are up to date.
9. Changes are mentioned in the changelog.

[codecov]

Codecov Report

Merging #3922 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3922   +/-   ##
=======================================
  Coverage   90.58%   90.58%           
=======================================
  Files         266      266           
  Lines       14528    14528           
  Branches     1455     1455           
=======================================
  Hits        13160    13160           
  Misses        941      941           
  Partials      427      427

---

Continue to review full report at Codecov.

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[codecov]

Codecov Report

Merging #3922 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3922   +/-   ##
=======================================
  Coverage   90.58%   90.58%           
=======================================
  Files         266      266           
  Lines       14528    14528           
  Branches     1455     1455           
=======================================
  Hits        13160    13160           
  Misses        941      941           
  Partials      427      427

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update f119681...0bf7450. Read the comment docs.