Auto update feature for PS6 doesn't support proxy

System Details

System Details Output

### VSCode version: 1.39.2 6ab598523be7a800d7f3eb4d92d7ab9a66069390 x64

### VSCode extensions:
aaron-bond.better-comments@2.0.5
cnojima.readable-indent@1.2.1
CoenraadS.bracket-pair-colorizer@1.0.61
DavidAnson.vscode-markdownlint@0.31.0
eamodio.gitlens@10.1.1
felipecaputo.git-project-manager@1.7.1
Gruntfuggly.todo-tree@0.0.160
humao.rest-client@0.22.2
ms-azure-devops.azure-pipelines@1.157.4
ms-azuretools.vscode-apimanagement@0.1.1
ms-azuretools.vscode-azureappservice@0.16.0
ms-azuretools.vscode-azurefunctions@0.19.0
ms-azuretools.vscode-azurestorage@0.7.2
ms-azuretools.vscode-cosmosdb@0.11.0
ms-azuretools.vscode-docker@0.8.1
ms-mssql.mssql@1.6.0
ms-vscode-remote.remote-wsl@0.39.9
ms-vscode.azure-account@0.8.6
ms-vscode.azurecli@0.4.6
ms-vscode.powershell@2019.9.0
ms-vscode.vscode-node-azure-pack@0.0.9
ms-vsts.team@1.149.2
msazurermtools.azurerm-vscode-tools@0.7.0
sdras.night-owl@1.1.3
Tyriar.theme-sapphire@0.9.1
vsciot-vscode.azure-iot-toolkit@2.11.0
vscode-icons-team.vscode-icons@9.4.0
waderyan.gitblame@3.0.1


### PSES version:

### PowerShell version:

Name                           Value
----                           -----
PSVersion                      6.2.3
PSEdition                      Core
GitCommitId                    6.2.3
OS                             Microsoft Windows 10.0.17763
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Issue Description

I am experiencing a problem with the auto update feature in PS extension for VSCode.

Expected Behaviour

If http.proxy and/or https.proxy is configured in any settings.json, the same proxy should be used with the Invoke-RestMethod -proxy

Actual Behaviour

Invoke-Restmethod with no -proxy will cause the auto update to fail as it can't download the installer.

Attached Logs

No logs, as I manually upgraded before saving them but you can clearly see what is happening in console that there is no -proxy etc.

Start by locating the extension's auto-update path and its Invoke-RestMethod call, then inspect how http.proxy and https.proxy from settings.json are exposed. Verify that the updater uses the configured proxy when downloading the installer, and confirm the update succeeds in a proxied environment.