Syntax Highlighting doesn't recognize ? as part of a variable name

Reproduce the reported syntax-highlighting issue with $test? = 5 and "$test?" in the PowerShell editor. Start by locating the PowerShell syntax-highlighting grammar or definition used by the extension, then verify that ? is treated as part of the variable name in both examples. Done means the corrected highlighting is covered by the relevant grammar test, if one exists.

Prerequisites

• I have written a descriptive issue title.
• I have searched all issues to ensure it has not already been reported.
• I have read the troubleshooting guide.
• I am sure this issue is with the extension itself and does not reproduce in a standalone PowerShell instance.
• I have verified that I am using the latest version of Visual Studio Code and the PowerShell extension.

Summary

Issue Type: Bug

? is a valid part of a variable name. Don't ask how I discovered this 😄

Extension version: 2022.1.0
VS Code version: Code 1.63.2 (899d46d82c4c95423fb7e10e68eba52050e30ba3, 2021-12-15T09:40:02.816Z)
OS version: Windows_NT x64 10.0.19044
Restricted Mode: No

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PowerShell Version

Name                           Value
----                           -----
PSVersion                      7.2.1
PSEdition                      Core
GitCommitId                    7.2.1
OS                             Microsoft Windows 10.0.19044       
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Visual Studio Code Version

1.63.2
899d46d82c4c95423fb7e10e68eba52050e30ba3
x64

Extension Version

powershell-preview@2022.01.0

Steps to Reproduce

$test? = 5
"$test?"

Visuals

No response

Logs

No response