Update JSON menu representation in mutations

[maarcingebala]

Storefront 1.0 uses json_content fields to render menus in its HTML templates (to optimize rendering and not fetch the whole structure from the database every time). Those fields were however not updated when using API mutations.

This PR introduces the following changes:

• adds update_menu and update_menus calls in mutations that touch menu items
• moves the utilty functions from saleor.dashboard.menu.utils to saleor.menu.utils as they're now used outside of dashboard 1.0 as well.

Also fixes #4471

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.

[NyanKiyoshi]

Maybe this PR could include a fix for #4471?

[dominik-zeglen]

Should be fixed long time ago

[NyanKiyoshi]

@dominik-zeglen the issue is not the dashboard, but the mutation not checking the user input 👍

[django-queries]

Here is the report for a801c56 (maarcingebala/saleor @ update-menu-json-in-api)
Base comparison is cf43e0e.

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                     	         41	         41	             20

# 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                     	         13	         13	              3

# api.benchmark variant
  test name                           	left count 	right count	duplicate count
  ------------------------------------	-----------	-----------	---------------
  retrieve variant list               	          9	          9	              2

[codecov]

Codecov Report

Merging #4524 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #4524      +/-   ##
==========================================
+ Coverage   90.64%   90.64%   +<.01%     
==========================================
  Files         297      297              
  Lines       17437    17411      -26     
  Branches     1748     1738      -10     
==========================================
- Hits        15805    15783      -22     
  Misses       1121     1121              
+ Partials      511      507       -4

Impacted Files	Coverage Δ
saleor/dashboard/menu/utils.py	100% <ø> (+9.23%)	⬆️
saleor/dashboard/page/views.py	94.44% <100%> (ø)	⬆️
saleor/graphql/menu/mutations.py	97.58% <100%> (+0.31%)	⬆️
saleor/graphql/menu/bulk_mutations.py	100% <100%> (ø)	⬆️
saleor/dashboard/menu/forms.py	84.74% <100%> (ø)	⬆️
saleor/dashboard/category/views.py	83.69% <100%> (ø)	⬆️
saleor/dashboard/collection/views.py	92.2% <100%> (ø)	⬆️
saleor/dashboard/menu/views.py	95.78% <100%> (+0.02%)	⬆️
saleor/payment/utils.py	90.47% <0%> (-0.87%)	⬇️

---

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[maarcingebala]

@NyanKiyoshi I also fixed the issue #4471 that you've mentioned.

[NyanKiyoshi]

We might want to update dashboard-next as well before merging, I think it is breaking it, right?

[maarcingebala]

@NyanKiyoshi What do you exactly mean by "updating dashboard-next"? I made fixes only in the backend.

[NyanKiyoshi]

@maarcingebala nevermind. At the time of reviewing the name field wasn't optional.

[NyanKiyoshi]

LGTM 👍