Add translations to countries in shop query

[fowczarek]

I want to merge this change because resolve #4622

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. GraphQL schema and type definitions are up to date.
8. Changes are mentioned in the changelog.

[django-queries]

Here is the report for 428b753 (mirumee/saleor @ 4622/Add_languagecode_parameter)
Base comparison is 2a6f85b.

No differences were found. (click me)

# api.benchmark checkout
  test name                           	left count 	right count	duplicate count
  ------------------------------------	-----------	-----------	---------------
  add billing address to checkout     	         34	         34	             20
  add shipping to checkout            	          7	          7	              0
  checkout payment charge             	         14	         14	              0
  complete checkout                   	          6	          6	              0
  create checkout                     	         48	         48	             24

# api.benchmark homepage
  test name                           	left count 	right count	duplicate count
  ------------------------------------	-----------	-----------	---------------
  retrieve main menu                  	          5	          5	              0
  retrieve product list               	          4	          4	              0
  retrieve secondary menu             	          5	          5	              0
  retrieve shop                       	          2	          2	              0

# api.benchmark product
  test name                           	left count 	right count	duplicate count
  ------------------------------------	-----------	-----------	---------------
  product details                     	         15	         15	              3

# api.benchmark variant
  test name                           	left count 	right count	duplicate count
  ------------------------------------	-----------	-----------	---------------
  retrieve variant list               	         18	         18	              8

[codecov]

Codecov Report

Merging #4732 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #4732      +/-   ##
==========================================
+ Coverage   91.67%   91.67%   +<.01%     
==========================================
  Files         313      313              
  Lines       18852    18855       +3     
  Branches     1851     1851              
==========================================
+ Hits        17283    17286       +3     
  Misses       1049     1049              
  Partials      520      520

Impacted Files	Coverage Δ
saleor/graphql/shop/types.py	95.89% <100%> (+0.08%)	⬆️

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[codecov]

Codecov Report

Merging #4732 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #4732      +/-   ##
==========================================
+ Coverage   91.67%   91.67%   +<.01%     
==========================================
  Files         313      313              
  Lines       18852    18855       +3     
  Branches     1851     1851              
==========================================
+ Hits        17283    17286       +3     
  Misses       1049     1049              
  Partials      520      520

Impacted Files	Coverage Δ
saleor/graphql/shop/types.py	95.89% <100%> (+0.08%)	⬆️

---

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 2a6f85b...428b753. Read the comment docs.