Added record struct and switch expression snippet, added a placeholder name for records

[TimothyMakkison]

Record struct snippets

Added snippets:

records - Mutable positional record struct

public record struct MyRecord(string Name);

recordsd - Mutable struct record with deconstructor

public record struct MyRecord
{
    public MyRecord(string name, int age) => (Name, Age) = (name, age);

    public string Name { get; set; }
    public int Age { get; set; }

    public void Deconstructor(out string name, out int age) => (name, age) = (Name, Age);
}

recordsr - Immutable positional record struct

public readonly record struct MyRecord(string Name);

Record changes

Changed the default type name for records from Person to a placeholder with the default text MyRecord. This should keep records inline with class and struct snippets. I'm not sure if this would be considered a breaking change as its adding another placeholder and may break muscle memory for users.

Switch expression snippet

Added a snippet for switch expressions from C# 8.0.

switche - Switch expression

value switch
{
    value1 => value2,
    _ => default,
};

Realigned the deconstructor for recordd and recordsd

From:

    ...
    public int Age { get; set; }

public void Deconstructor(out string name, out int age) => (name, age) = (Name, Age);
}

    ...
    public int Age { get; set; }

    public void Deconstructor(out string name, out int age) => (name, age) = (Name, Age);
}