feat(core): Add 'Get-Encoding()' function to fix missing webClient encoding

[yi-Xu-0100]

Add Get-Encoding function in core.ps1

Description

Motivation and Context

Closes #4911 #4324

Relates to #4911 #4324

How Has This Been Tested?

Checklist:

• I have read the Contributing Guide.
• I have ensured that I am targeting the develop branch.
• I have updated the documentation accordingly.
• I have updated the tests accordingly.
• I have added an entry in the CHANGELOG.

[yi-Xu-0100]

@rashil2000 Any review here will be helpful~ 😁

[niheaven]

Do you have some testing manifests?

[yi-Xu-0100]

@niheaven ,Thanks for your reply. 😁

In #4911 (comment) , I use

scoop install "https://raw.githubusercontent.com/ygguorun/scoop-bucket/master/bucket/PDFPatcher.json"

, and this manifest - DoveBoy/Apps/pdfpatcher has the checkver, and they all work well.

[niheaven]

checkver has some error, could you please check it again?

[yi-Xu-0100]

@niheaven I used it for scoop update and scoop install, they all work well.

Could you please provider the way to test the checkver, I have no idea for it.🤔

[niheaven]

Checkout this branch and cd in any bucket, run .\bin\checkver.ps1 xxx, there are some bugs :)

[yi-Xu-0100]

@niheaven Thanks for pointing out the problem, I think it's fixed now. 😁

[niheaven]

Some tweaks, and please test it @yi-Xu-0100

[yi-Xu-0100]

@niheaven Thanks for adding the judgment for null values, but there is something we need to revert.

If we use (Get-Encoding($wc)).GetString($wc.DownloadData($url)), then (Get-Encoding($wc)) can only get the return result in UTF-8, because The ResponseHeaders of $wc will be $null before the data is downloaded.

So I re-split the expression to handle the case where charset is something else.

[niheaven]

Aha, right?

Okay, I'll test it tomorrow and it seems stable enough now.