Compress-PSResource -PassThru now passes FileInfo instead of string

[jshigetomi]

PR Summary

Fixes: #1708

This pull request introduces several changes to the CompressPSResource cmdlet and its associated tests to enhance functionality and improve test coverage. The most significant changes include adding an output type to the cmdlet, modifying the cmdlet to return a FileInfo object, and expanding the test suite to verify these changes.

Enhancements to CompressPSResource cmdlet:

• Added [OutputType(typeof(FileInfo))] attribute to the CompressPSResource cmdlet to specify the output type. (src/code/CompressPSResource.cs)
• Modified the PackNupkg method to return a FileInfo object instead of a string path when the -PassThru parameter is used. (src/code/PublishHelper.cs)

Improvements to tests:

• Updated the test for Compress-PSResource -PassThru to check that the cmdlet returns a FileInfo object with the correct path and properties. (test/PublishPSResourceTests/CompressPSResource.Tests.ps1)

Code cleanup:

• Removed an unused using directive for System.Linq in CompressPSResource.cs. (src/code/CompressPSResource.cs)

PR Context

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