ReviewUnusedParameter does not capture parameter usage within a scriptblock

Steps to reproduce

Run Invoke-ScriptAnalyzer against the following with the new 1.19.0 release.

function foo {
    Param(
        $MyParameter
    )

    Get-Item| ForEach-Object { Get-ChildItem $MyParameter }
}

Expected behavior

No rule violations.

Actual behavior

The new ReviewUnusedParameter rule doesn't notice the usage. I suspect this is similar to the limitation of the AvoidUsingCmdletAliases rule though. Not sure if we should relax the ReviewUnusedParameter rule in this case to search nested scriptblocks inside a function scope.
cc @mattmcnabb @rjmholt @JamesWTruher

RuleName                            Severity     ScriptName Line  Message
--------                            --------     ---------- ----  -------
PSReviewUnusedParameter             Warning      test.ps1   4     The parameter 'MyParameter' has been declared but not used.

If an unexpected error was thrown then please report the full error details using e.g. $error[0] | Select-Object *

Environment data

> $PSVersionTable
Name                           Value
----                           -----
PSVersion                      7.1.0-preview.2
PSEdition                      Core
GitCommitId                    7.1.0-preview.2
OS                             Microsoft Windows 10.0.18363
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

> (Get-Module -ListAvailable PSScriptAnalyzer).Version | ForEach-Object { $_.ToString() }
1.19.0

从 ReviewUnusedParameter 规则开始，针对 issue 中所示的 PowerShell 函数运行 Invoke-ScriptAnalyzer，以复现报告。跟踪跨嵌套 scriptblocks 检测参数使用情况的过程，然后验证该示例不会产生 PSReviewUnusedParameter 违规。