Allow staff member to receive notification about customers orders

[kswiatek92]

closes #4932

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.

[IKarbowiak]

Maybe some tests for StaffNotification mutations and collect_staff_data_for_email function?

[kswiatek92]

Maybe some tests for StaffNotification mutations and collect_staff_data_for_email function?

i'm working on some tests :P

[codecov]

Codecov Report

Merging #4993 into master will increase coverage by 0.03%.
The diff coverage is 98.07%.

@@            Coverage Diff             @@
##           master    #4993      +/-   ##
==========================================
+ Coverage   90.85%   90.89%   +0.03%     
==========================================
  Files         294      294              
  Lines       18170    18269      +99     
  Branches     1671     1679       +8     
==========================================
+ Hits        16508    16605      +97     
- Misses       1227     1228       +1     
- Partials      435      436       +1

Impacted Files	Coverage Δ
saleor/graphql/shop/types.py	96.84% <100%> (+0.1%)	⬆️
saleor/account/models.py	89.93% <100%> (+0.39%)	⬆️
saleor/graphql/account/types.py	95.61% <100%> (+0.24%)	⬆️
saleor/order/emails.py	100% <100%> (ø)	⬆️
saleor/checkout/utils.py	83.83% <100%> (+0.02%)	⬆️
saleor/graphql/shop/schema.py	100% <100%> (ø)	⬆️
saleor/graphql/shop/mutations.py	96.2% <96.49%> (+0.02%)	⬆️

---

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[django-queries]

Here is the report for 348dff0 (kswiatek92/saleor @ receive-notification-about-customers-order)
Base comparison is 4a34733.

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                            	         50	         50	             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
  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                      	         15	         15	              6

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

[NyanKiyoshi]

LGTM

Requested changes were made.