Character based key handlers are not surrogate pair aware

[SeeminglyScience]

Environment

PS version: 7.0.0
PSReadline version: 2.0.0
os: 10.0.18362.1 (WinBuild.160101.0800)
PS file version: 7.0.0.0
HostName: ConsoleHost
BufferWidth: 140
BufferHeight: 3000

Exception report

Steps to reproduce

1. Copy a surrogate pair to clipboard (like 😀)
2. In a terminal that supports emojis, paste it
3. Press Backspace

Expected behavior

The buffer is empty.

Actual behavior

The buffer contains the high surrogate of the pasted surrogate pair.

---

This also applies to most character level handlers, including:

• ForwardChar
• BackwardChar
• DeleteChar
• Delete

And their VI variants.

[daxian-dbw]

For me later:
Reference to the related issue: #1329

[SeeminglyScience]

@nu8 that's not especially on topic to be honest. Most folks aren't going to stop using PowerShell so that they can type emojis a little better. Either way though this isn't really the place to pitch it.