Share version deduction code between packaging scripts

[nwhite-riot]

Packaging scripts should have shared logic to determine the current version so that they can handle search etc. better. This is an issue if developers are running the scripts locally and have leftover files from previous versions of the plugin (e.g. 0.22 and 1.00-alpha.3)

Plugin spec and version are handled in pack.ps1 here:

sentry-unreal/scripts/packaging/pack.ps1

Lines 52 to 53 in 83bbb57

	$pluginSpec = Get-Content "plugin-dev/Sentry.uplugin"
	$version = [regex]::Match("$pluginSpec", '"VersionName": "([^"]+)"').Groups[1].Value

... but test-contents.ps1 uses wildcard for plugin version:

sentry-unreal/scripts/packaging/test-contents.ps1

Line 24 in 83bbb57

$packages = Get-ChildItem "$projectRoot/sentry-unreal-*-$publishingPlatform.zip"