Garbled code is shown when opening changes in source control if a file is encoded with UTF-16 LE

[tonkon]

• VSCode Version: Code 1.18.1 (929bacb, 2017-11-16T18:32:36.023Z)
• OS Version: Windows_NT x64 10.0.15063
• Extensions:

Extension	Author (truncated)	Version
azuretoolsforvscode	bra	1.3.0
githistory	don	0.2.3
gitlens	eam	6.2.0
vscode-great-icons	emm	2.1.20
azure-functions-tools	joh	0.3.1
prettify-json	moh	0.0.3
vscode-azureappservice	ms-	0.4.0
vscode-azurefunctions	ms-	0.2.0
vscode-cosmosdb	ms-	0.2.1
mssql	ms-	1.2.1
azure-account	ms-	0.2.2
azurecli	ms-	0.3.0
csharp	ms-	1.13.1
PowerShell	ms-	1.5.1
vscode-azureextensionpack	ms-	0.0.7
team	ms-	1.122.0
azurerm-vscode-tools	msa	0.3.7
vscode-docker	Pet	0.0.22
vscode-hexdump	sle	1.6.0
usql-vscode-ext	usq	0.2.7
application-insights	Vis	0.4.1
azure-iot-toolkit	vsc	0.4.2

(1 theme extensions excluded)

---

Steps to Reproduce:

1. Initial a Git repo
2. Open the repo by VS Code and create a new JSON file, save with encoding UTF-16 LE
3. Commit the JSON file
4. Change a little bit in the JSON file
5. Go to "Source Control" view, double click the file and the garbled code will be shown.
   

Reproduces without extensions: Yes/No

[joaomoreno]

#21146