Set string environment variable (e.g., $env:JAVA_HOME) to most-recently-created subdirectory

Set-JavaHome.ps1

# So, we're not dependent on filename sort order ("9" > "10").

if (Test-Path "c:/usr/local/Java") {
    $env:JAVA_HOME = $(ls c:/usr/local/Java | sort CreationTime -desc | select -first 1 FullName).FullName
}
else {
    Write-Warning "No Java"
}

# TODO: could probably use a list of directories to search (e.g., @("c:/usr/local/Java", "c:/Program Files/Java")).