Make all functions use the default proxy(if the proxy was enabled) when no proxy specified

Bắt đầu bằng cách tái hiện việc đăng ký kho lưu trữ ps với proxy hệ thống được bật và không có proxy tường minh, sử dụng các phiên bản PowerShellGet và PackageManagement được hiển thị. Theo dõi yêu cầu đăng ký và các hàm liên quan để xác định nơi việc xử lý proxy bị khác biệt. Được xem là hoàn tất khi việc đăng ký kho lưu trữ thành công thông qua proxy mặc định đang được bật nếu không cung cấp đối số proxy nào, với độ bao phủ cho hành vi bị ảnh hưởng.

Expected Behavior

register the ps repository successfully

Current Behavior

nothing happened

Possible Solution

when no proxy specified, then invoke the default proxy (when the proxy was enabled)
https://stackoverflow.com/questions/571429/powershell-web-requests-and-proxies

Steps to Reproduce (for bugs)

set the proxy on computer

Context

related to https://github.com/PowerShell/WindowsCompatibility/issues/45
I want to register ps repository

Your Environment

> $PSVersionTable
Name                           Value
----                           -----
PSVersion                      6.1.0
PSEdition                      Core
GitCommitId                    6.1.0
OS                             Microsoft Windows 10.0.16299
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0
> Get-Module
ModuleType Version    Name                                ExportedCommands
---------- -------    ----                                ----------------
Script     0.0        build                               {Clear-PSRepo, Compress-TestContent, Convert-TxtResourceToXml, ConvertFrom-PesterLog...}
Script     0.0        chuck                               Reset-FolderTime
Script     0.0        Get-PSGalleryApiAvailability
Manifest   6.1.0.0    Microsoft.PowerShell.Management     {Add-Content, Clear-Content, Clear-Item, Clear-ItemProperty...}
Manifest   6.1.0.0    Microsoft.PowerShell.Management     {Add-Content, Clear-Content, Clear-Item, Clear-ItemProperty...}
Manifest   6.1.0.0    Microsoft.PowerShell.Security       {ConvertFrom-SecureString, ConvertTo-SecureString, Get-Acl, Get-AuthenticodeSignature...}
Manifest   6.1.0.0    Microsoft.PowerShell.Utility        {Add-Member, Add-Type, Clear-Variable, Compare-Object...}
Manifest   6.1.0.0    Microsoft.WSMan.Management          {Connect-WSMan, Disable-WSManCredSSP, Disconnect-WSMan, Enable-WSManCredSSP...}
Script     1.1.7.2    PackageManagement                   {Find-Package, Find-PackageProvider, Get-Package, Get-PackageProvider...}
Script     1.0.0.0    posh-git                            {Add-PoshGitToProfile, Expand-GitCommand, Format-GitBranchName, Get-GitBranchStatusColor...}
Script     2.0.1      PowerShellGet                       {Find-Command, Find-DscResource, Find-Module, Find-RoleCapability...}
Script     2.0.0      PSReadLine                          {Get-PSReadLineKeyHandler, Get-PSReadLineOption, Remove-PSReadLineKeyHandler, Set-PSReadLineKeyHandler...}
> Get-Module -ListAvailable PowerShellGet,PackageManagement
ModuleType Version    Name                                PSEdition ExportedCommands
---------- -------    ----                                --------- ----------------
Script     1.1.7.2    PackageManagement                   Desk      {Find-Package, Get-Package, Get-PackageProvider, Get-PackageSource...}
Script     1.6.7      PowerShellGet                       Desk      {Find-Command, Find-DSCResource, Find-Module, Find-RoleCapability...}
> Get-PackageProvider
Name                     Version          DynamicOptions
----                     -------          --------------
NuGet                    2.8.5.210        Destination, ExcludeVersion, Scope, SkipDependencies, Headers, FilterOnTag, Contains, AllowPrereleaseVersions, ConfigFile, SkipValidate
PowerShellGet            1.6.7.0          PackageManagementProvider, Type, Scope, AllowClobber, SkipPublisherCheck, InstallUpdate, NoPathUpdate, AllowPrereleaseVersions, Filter, Tag, Includes, DscResource, RoleCapability, Command, Ac...
> Get-PackageProvider -ListAvailable
Name                     Version          DynamicOptions
----                     -------          --------------
NuGet                    2.8.5.210        Destination, ExcludeVersion, Scope, SkipDependencies, Headers, FilterOnTag, Contains, AllowPrereleaseVersions, ConfigFile, SkipValidate
PowerShellGet            1.6.7.0          PackageManagementProvider, Type, Scope, AllowClobber, SkipPublisherCheck, InstallUpdate, NoPathUpdate, AllowPrereleaseVersions, Filter, Tag, Includes, DscResource, RoleCapability, Command, Ac...