Add user avatar management

[benekex2]

I want to merge this change because its add user avatar managment

Resolves #3921

Screenshots

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 #4030 into master will increase coverage by 0.09%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4030      +/-   ##
==========================================
+ Coverage   91.28%   91.37%   +0.09%     
==========================================
  Files         275      274       -1     
  Lines       14955    14947       -8     
  Branches     1450     1451       +1     
==========================================
+ Hits        13651    13658       +7     
+ Misses        913      898      -15     
  Partials      391      391

Impacted Files	Coverage Δ
saleor/graphql/core/decorators.py
saleor/graphql/checkout/mutations.py	93.42% <0%> (+0.06%)	⬆️
saleor/checkout/forms.py	96.02% <0%> (+0.64%)	⬆️

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