Implement Enumerable.*By methods (DistinctBy, ExceptBy, IntersectBy, UnionBy, MinBy, MaxBy)

[eiriktsarpalis]

Fix #27687.

Note that the implementation does not include the following overloads:

public static IEnumerable<TSource> ExceptBy<TSource, TKey>(this IEnumerable<TSource> first, IEnumerable<TSource> second, Func<TSource, TKey> keySelector);
public static IEnumerable<TSource> ExceptBy<TSource, TKey>(this IEnumerable<TSource> first, IEnumerable<TSource> second, Func<TSource, TKey> keySelector, IEqualityComparer<TKey>? comparer);

public static IEnumerable<TSource> IntersectBy<TSource, TKey>(this IEnumerable<TSource> first, IEnumerable<TSource> second, Func<TSource, TKey> keySelector);
public static IEnumerable<TSource> IntersectBy<TSource, TKey>(this IEnumerable<TSource> first, IEnumerable<TSource> second, Func<TSource, TKey> keySelector, IEqualityComparer<TKey>? comparer);

I have decided to remove them since they were causing type inference issues and can be expressed trivially in terms of the other ExceptBy and IntersectBy overloads.

[dotnet-issue-labeler]

Note regarding the new-api-needs-documentation label:

This serves as a reminder for when your PR is modifying a ref *.cs file and adding/modifying public APIs, to please make sure the API implementation in the src *.cs file is documented with triple slash comments, so the PR reviewers can sign off that change.

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Issue Details

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Fix #27687.

Note that the implementation does not include the following overloads:

public static IEnumerable<TSource> ExceptBy<TSource, TKey>(this IEnumerable<TSource> first, IEnumerable<TSource> second, Func<TSource, TKey> keySelector);
public static IEnumerable<TSource> ExceptBy<TSource, TKey>(this IEnumerable<TSource> first, IEnumerable<TSource> second, Func<TSource, TKey> keySelector, IEqualityComparer<TKey>? comparer);

public static IEnumerable<TSource> IntersectBy<TSource, TKey>(this IEnumerable<TSource> first, IEnumerable<TSource> second, Func<TSource, TKey> keySelector);
public static IEnumerable<TSource> IntersectBy<TSource, TKey>(this IEnumerable<TSource> first, IEnumerable<TSource> second, Func<TSource, TKey> keySelector, IEqualityComparer<TKey>? comparer);

I have decided to remove them since they were causing type inference issues and can be expressed trivially in terms of the other ExceptBy and IntersectBy overloads.

Author:	eiriktsarpalis
Assignees:	eiriktsarpalis
Labels:	area-System.Linq
Milestone:	6.0.0