Allow sorting warehouses by name

[dominik-zeglen]

I want to merge this change because it adds sorting to warehouses.

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 9147491 (mirumee/saleor @ add/warehouse-sorting)
Base comparison is d4016eb.

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                    	         10	         10	              0
  complete checkout                          	          8	          8	              0
  create checkout                            	          5	          5	              1

# 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                            	         18	         18	              4
  retrieve product attributes                	          9	          9	              0

# api.benchmark variant
  test name                                  	left count 	right count	duplicate count
  -------------------------------------------	-----------	-----------	---------------
  product variant bulk create                	         51	         51	              3
  retrieve variant list                      	         23	         23	              9

# api product sorting attributes
  test name                                  	left count 	right count	duplicate count
  -------------------------------------------	-----------	-----------	---------------
  sort product not having attribute data     	         21	         21	              0

[codecov]

Codecov Report

Merging #5211 into master will decrease coverage by 0.01%.
The diff coverage is 82.6%.

@@            Coverage Diff             @@
##           master    #5211      +/-   ##
==========================================
- Coverage    91.8%   91.78%   -0.02%     
==========================================
  Files         270      271       +1     
  Lines       17540    17562      +22     
  Branches     1523     1525       +2     
==========================================
+ Hits        16102    16120      +18     
- Misses       1040     1042       +2     
- Partials      398      400       +2

Impacted Files	Coverage Δ
saleor/graphql/warehouse/schema.py	96% <77.77%> (-4%)	⬇️
saleor/graphql/warehouse/sorters.py	85.71% <85.71%> (ø)

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