Performance improvements for find/install

[SydneyhSmith]

Summary of the new feature / enhancement

Based on the investigation in issue PowerShell/PowerShellGet#641 we have come to the following ideas:

• Fix IEnumerable issues PowerShell/PowerShellGet#654
• Refactor Find to use IRepositorySearch (with current nuget APIs) PowerShell/PowerShellGet#655
• (optionally) Look at IDownloadPackage refactor
• Use Find local cache PowerShell/PowerShellGet#613
• Look at new implementations using HTTPClient

Proposed technical implementation details (optional)

No response

[JustinGrote]

@SydneyhSmith PowerShell/PowerShellGallery#241 might be related at least for powershell gallery "Az*" searches.

[JustinGrote]

Even though I implemented it in native powershell, you may want to look at how I used a native httpclient to speed up installs of the Az module from 2 minutes to 5 seconds :).

The same logic can easily apply to C# and can be much faster if the awaitable tasks are chained together (which I can't really feasibly do in PowerShell)

https://github.com/JustinGrote/ModuleFast/blob/main/ModuleFast.ps1

[alerickson]

closing this in favor of #655