Added array support for pointer-permissions

[Dobbias]

This adds the ability to provide array columns to 'readUserFields' or 'writeUserFields'.
All Pointer<_User> in the array stored in the object field are granted the read and/or write permission.

This extends the pointer permissions without affecting the ability of using single Pointer<_User> columns.

This functionality is also needed for future additions to the protected fields as discussed in pull request #5887

[Dobbias]

The build for PostgreSQL currently fails since it doesn't support the $all query operator for objects. This is currently used since the pointer-permissions array stores the users as Pointer<_User>. As far as is understand there are two options:

1. Make this feature MongoDB exclusive
2. Store the object ids of the users in the pointer-permissions array instead of the actual pointer and use $all with a regex (checking for the userId)

The advantage of 2. is that it should work on both dbs. The advantage of 1. is that it's coherent with the one-user pointer-permissions which uses columns of the type Pointer<_User>.

I would go with number 2. Or is 1 the way to go?

[dplewis]

@Dobbias Thank for starting on this PR. I don't know much about permissions but I can look into postgres for you. $all could be transformed to and if I remember correctly.

[codecov]

Codecov Report

Merging #5921 into master will decrease coverage by 0.02%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #5921      +/-   ##
==========================================
- Coverage   93.72%   93.69%   -0.03%     
==========================================
  Files         153      156       +3     
  Lines       10801    10866      +65     
==========================================
+ Hits        10123    10181      +58     
- Misses        678      685       +7

Impacted Files	Coverage Δ
src/Controllers/SchemaController.js	96.37% <ø> (ø)	⬆️
src/Controllers/DatabaseController.js	94.8% <100%> (-0.01%)	⬇️
...dapters/Storage/Postgres/PostgresStorageAdapter.js	96.68% <100%> (+0.01%)	⬆️
src/GraphQL/ParseGraphQLServer.js	93.02% <0%> (-4.42%)	⬇️
src/Adapters/Storage/Mongo/MongoStorageAdapter.js	92.23% <0%> (-0.71%)	⬇️
src/GraphQL/loaders/parseClassTypes.js	85.26% <0%> (-0.71%)	⬇️
src/GraphQL/loaders/objectsMutations.js	97.5% <0%> (-0.5%)	⬇️
src/GraphQL/loaders/usersQueries.js	96.87% <0%> (ø)	⬆️
src/RestWrite.js	93.72% <0%> (ø)	⬆️
src/GraphQL/transformers/query.js	46.87% <0%> (ø)
... and 9 more

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[dplewis]

use $all with a regex

@Dobbias That code was already there so the Postgres fix was easy.
This fix doesn't use regex.

https://github.com/parse-community/parse-server/blob/master/src/Adapters/Storage/Postgres/PostgresStorageAdapter.js#L478