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Add C# 10 to language history (#4996)

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Features Added in C# Language Versions
====================
# C# 10.0 - .NET 6 and Visual Studio 2022 version 17.0
- [Record structs](https://github.com/dotnet/csharplang/blob/master/proposals/csharp-10.0/record-structs.md) and `with` expressions on structs (`record struct Point(int X, int Y);`, `var newPoint = point with { X = 100 };`).
- [Global using directives](https://github.com/dotnet/csharplang/blob/master/proposals/csharp-10.0/GlobalUsingDirective.md): `global using` directives avoid repeating the same `using` directives across many files in your program.
- [Improved definite assignment](https://github.com/dotnet/csharplang/blob/main/proposals/csharp-10.0/improved-definite-assignment.md): definite assignment and nullability analysis better handle common patterns such as `dictionary?.TryGetValue(key, out value) == true`.
- [Constant interpolated strings](https://github.com/dotnet/csharplang/blob/main/proposals/csharp-10.0/constant_interpolated_strings.md): interpolated strings composed of constants are themselves constants.
- [Extended property patterns](https://github.com/dotnet/csharplang/blob/main/proposals/csharp-10.0/extended-property-patterns.md): property patterns allow accessing nested members (`if (e is MethodCallExpression { Method.Name: "MethodName" })`).
- [Sealed record ToString](https://github.com/dotnet/csharplang/issues/4174): a record can inherit a base record with a sealed `ToString`.
- [Incremental source generators](https://github.com/dotnet/roslyn/blob/main/docs/features/incremental-generators.md): improve the source generation experience in large projects by breaking down the source generation pipeline and caching intermediate results.
- [Mixed deconstructions](https://github.com/dotnet/csharplang/issues/125): deconstruction-assignments and deconstruction-declarations can be blended together (`(existingLocal, var declaredLocal) = expression`).
- [Method-level AsyncMethodBuilder](https://github.com/dotnet/csharplang/blob/main/proposals/csharp-10.0/async-method-builders.md): the AsyncMethodBuilder used to compile an `async` method can be overridden locally.
- [#line span directive](https://github.com/dotnet/csharplang/blob/main/proposals/csharp-10.0/enhanced-line-directives.md): allow source generators like Razor fine-grained control of the line mapping with `#line` directives that specify the destination span (`#line (startLine, startChar) - (endLine, endChar) charOffset "fileName"`).
- [Lambda improvements](https://github.com/dotnet/csharplang/blob/main/proposals/csharp-10.0/lambda-improvements.md): attributes and return types are allowed on lambdas; lambdas and method groups have a natural delegate type (`var f = short () => 1;`).
- [Interpolated string handlers](https://github.com/dotnet/csharplang/blob/main/proposals/csharp-10.0/improved-interpolated-strings.md): interpolated string handler types allow efficient formatting of interpolated strings in assignments and invocations.
- [File-scoped namespaces](https://github.com/dotnet/csharplang/blob/main/proposals/csharp-10.0/file-scoped-namespaces.md): files with a single namespace don't need extra braces or indentation (`namespace X.Y.Z;`).
- [Parameterless struct constructors](https://github.com/dotnet/csharplang/blob/main/proposals/csharp-10.0/parameterless-struct-constructors.md): support parameterless constructors and instance field initializers for struct types.
- [CallerArgumentExpression](https://github.com/dotnet/csharplang/blob/main/proposals/csharp-10.0/caller-argument-expression.md): this attribute allows capturing the expressions passed to a method as strings.
# C# 9.0 - .NET 5 and Visual Studio 2019 version 16.8
- [Records](https://github.com/dotnet/csharplang/blob/master/proposals/csharp-9.0/records.md) and `with` expressions: succinctly declare reference types with value semantics (`record Point(int X, int Y);`, `var newPoint = point with { X: 100 }`).
- [Records](https://github.com/dotnet/csharplang/blob/master/proposals/csharp-9.0/records.md) and `with` expressions: succinctly declare reference types with value semantics (`record Point(int X, int Y);`, `var newPoint = point with { X = 100 };`).
- [Init-only setters](https://github.com/dotnet/csharplang/blob/master/proposals/csharp-9.0/init.md): init-only properties can be set during object creation (`int Property { get; init; }`).
- [Top-level statements](https://github.com/dotnet/csharplang/blob/master/proposals/csharp-9.0/top-level-statements.md): the entry point logic of a program can be written without declaring an explicit type or `Main` method.
- [Pattern matching enhancements](https://github.com/dotnet/csharplang/blob/master/proposals/csharp-9.0/patterns3.md): relational patterns (`is < 30`), combinator patterns (`is >= 0 and <= 100`, `case 3 or 4:`, `is not null`), parenthesized patterns (`is int and (< 0 or > 100)`), type patterns (`case Type:`).