[Proposal]: Allow new-lines in all interpolations

[CyrusNajmabadi]

Allow new-lines in all interpolations

• Specification: https://github.com/dotnet/csharplang/blob/main/proposals/csharp-11.0/new-line-in-interpolation.md
• Discussion: [Proposal]: Remove restriction that interpolations within a non-verbatim interpolated string cannot contain new-lines. #8648

Summary

Allow user to have multi-line interpolations in all places where interpolations are allowed. For example:

var v = $"Count is\t: { this.Is.A.Really()
                            .That.I.Should(
                                be + able)[
                                    to.Wrap()] }.";

Design meetings

main/meetings/2021/LDM-2021-09-20.md