Document GraphQL changes between 3.x and 4.x

[adriendupuis]

Question	Answer
JIRA Ticket	CS-12208
Versions	All (related to 4.6 but documented on every branches)
Edition	All

GraphQL had some compatibility breaking changes between (what seems to be) 3.3 and 4.0 (circa ezsystems/ezplatform-graphql#90)

• Ibexa DXP 3.3.41 uses ezsystems/ezplatform-graphql 2.3.17
• ezsystems/ezplatform-graphql 3.0 became ibexa/graphql 4.0
• Ibexa DXP 4.6 uses ibexa/graphql 4.6

Preview: https://ez-systems-developer-documentation--2572.com.readthedocs.build/en/2572/update_and_migration/from_3.3/to_4.0/#graphql

TODO:

• [ ] Confirm that it's between 3.3 and 4.0 and not a latter 4.x
• [ ] Analyse more ibexa/ezplatform-graphql#90 and possible related PR to make sure every changes is covered.
• [ ] Wait for IBX-9368 then produce more locations with conditional field examples.

Checklist

• [ ] Text renders correctly
• [ ] Text has been checked with vale
• [ ] Description metadata is up to date
• [ ] Redirects cover removed/moved pages
• [ ] Code samples are working
• [ ] PHP code samples have been fixed with PHP CS fixer
• [ ] Added link to this PR in relevant JIRA ticket or code PR