Entity equality: Contains and OrderBy

[roji]

Closes #15939

For Contains, I realized half-way through that the test (Contains_over_entityType_should_rewrite_to_identity_equality) depends on #15855, since the second query sends the ID selected in the first query. Am still submitting the implementation - the expression tree generated internally looks good. I can also hold off until #15855 is done.

Also, I tested the case Orders.Contains(null) and was surprised to see the null is parameterized. Is this intended?

Finally, unrelated to EE: I understand the need to split into two queries for Single, since the 1-element verification needs to happen client-side. However, for First, FOD, Last, LOD we can translate as a single query:

SELECT (
    SELECT TOP(1) [o].[OrderID]
    FROM [Orders] AS [o]
    WHERE [o].[OrderID] = 10248)
IN (
    SELECT [o].[OrderID]
    FROM [Orders] AS [o]
    WHERE [o].[CustomerID] = N'VINET'
)");

(this is PostgreSQL, SQLServer requires the surrounding CASE for boolean). Is this optimization already tracked somewhere, should I open an issue?

For OrderBy, note that I've implemented support for composite keys, where we split the comparison into multiple OrderBy().ThenBy() operators.

[smitpatel]

This build was failing with error

Microsoft.EntityFrameworkCore.ApiConsistencyTest.Public_api_bool_parameters_should_not_be_prefixed
\r\n-- Prefixed bool parameters --\r\nMicrosoft.EntityFrameworkCore.Query.Pipeline.EntityEqualityRewritingExpressionVisitor.<VisitOrderingMethodCall>g__GetOrderingMethodInfo|18_0[isFirstOrdering]\r\nMicrosoft.EntityFrameworkCore.Query.Pipeline.EntityEqualityRewritingExpressionVisitor.<VisitOrderingMethodCall>g__GetOrderingMethodInfo|18_0[isAscending]\r\nExpected: False\r\nActual:   True
   at Microsoft.EntityFrameworkCore.ApiConsistencyTestBase.Public_api_bool_parameters_should_not_be_prefixed() in D:\code\EntityFrameworkCore\test\EFCore.Tests\ApiConsistencyTestBase.cs:line 248

Build break fixed in aafc355