Optimize VisitList<>()

[SergeiPavlov]

Most usage case don't require IReadOnlyList<>.

IEnumerable<> is enough. This allows to avoid allocating intermediate arrays when unnecessary

[Copilot]

Pull Request Overview

This PR optimizes the transformation of element lists in expression visitors to avoid unnecessary intermediate allocations. Key changes include converting Visit*List methods to yield IEnumerable, refactoring VisitList to return the original collection when possible, and adding a ToReadOnlyList extension to support compatibility with APIs expecting IReadOnlyList.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
Orm/Xtensive.Orm/Orm/Linq/Expressions/Visitors/OwnerRemover.cs	Applies ToReadOnlyList conversion to adapt to changes in VisitList return type.
Orm/Xtensive.Orm/Linq/ExpressionVisitor.cs	Changes Visit*List methods' return types from IReadOnlyList to IEnumerable and refactors VisitList.
Orm/Xtensive.Orm/Core/Extensions/EnumerableExtensions.cs	Introduces ToReadOnlyList extension to convert IEnumerable sequences to IReadOnlyList.

Comments suppressed due to low confidence (2)

Orm/Xtensive.Orm/Orm/Linq/Expressions/Visitors/OwnerRemover.cs:70

• Verify that converting newConstructorArguments to a read-only list at this point is necessary, as it might introduce an extra allocation if newConstructorArguments is already an IReadOnlyList. Consider ensuring that the conversion is applied consistently with the intended performance benefits.

return new ConstructorExpression(expression.Type, bindings, nativeBingings, expression.Constructor, newConstructorArguments.ToReadOnlyList());

Orm/Xtensive.Orm/Linq/ExpressionVisitor.cs:246

• [nitpick] The refactored VisitList now defers transformation via lazy evaluation which may result in multiple invocations of func for the later elements. Ensure that func is side-effect free and has acceptable performance characteristics, or consider materializing the results immediately if multiple enumerations are expected.

if (func(originalValue) is var p && !ReferenceEquals(p, originalValue)) {

[botinko]

            IList<T> list => list.Count is var count && count == 0
                ? []
                : ReferenceArraySegment<T>.TryCreate(list, count) ?? new ReadOnlyCollection<T>(list),

in mono we have optimization for empty List