Allow derived inclusion chains in filter/sort/page query strings

[bkoelman]

This PR adds support for using derived inclusion chains in filter/sort/page query string parameters.

For example:

[Resource]
public abstract class Vehicle : Identifiable<long>
{
}

[Resource]
public sealed class Boat : Vehicle
{
}

[Resource]
public sealed class Car : Vehicle
{
    [HasMany]
    public ISet<Wheel> Wheels { get; set; } = new HashSet<Wheel>();
}

[Resource]
public sealed class Wheel : Identifiable<long>
{
    [Attr]
    public decimal Radius { get; set; }
}

The following query now applies the specified filter only on cars:

GET /vehicles?include=wheels&filter[wheels]=greaterThan(radius,'5')

Before, the request would fail with HTTP 400:

The specified filter is invalid.
Field 'wheels' does not exist on resource type 'vehicles'.

Minor breaking API changes:

• QueryStringParameterScopeExpression.Scope: Type changed from ResourceFieldChainExpression? to IncludeExpression?.
• PaginationElementQueryStringValueExpression.Scope: Type changed from ResourceFieldChainExpression? to IncludeExpression?.
• IQueryStringParameterScopeParser.Parse: removed pattern and options parameters.
• IncludeParser.ParseInclude / QueryStringParameterScopeParser.ParseQueryStringParameterScope: removed source parameter, which is now available as a property on the base class.

The breaking changes are required to support multiple derived relationships in an inclusion chain. Parsing scopes in filter/sort/page now works similarly to how the value of the include query string parameter is parsed.

For example, assume that type Truck also has a Wheels to-many relationship. The wheels scope in filter[wheels] is now parsed into two inclusion chains: one for Car and one for Truck, so that the filter can be applied to both. To visualize the change, call ToFullString() on the expression.

Fixes #1642.

QUALITY CHECKLIST

• Changes implemented in code
• Complies with our contributing guidelines
• Adapted tests
• N/A: Documentation updated

[bkoelman]

Holding off on the merge until the coverage diff works again. Tracked at codecov/codecov-action#1852.

[codecov]

Codecov Report

❌ Patch coverage is 96.68874% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.06%. Comparing base (f20d94d) to head (fb82615).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...otNetCore/Queries/Parsing/QueryExpressionParser.cs	94.89%	3 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1756      +/-   ##
==========================================
- Coverage   92.06%   92.06%   -0.01%     
==========================================
  Files         475      475              
  Lines       14699    14722      +23     
  Branches     2322     2331       +9     
==========================================
+ Hits        13533    13554      +21     
- Misses        765      766       +1     
- Partials      401      402       +1     

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