Add Pull Request plugin

The plugin adds support for automatically creating a GitHub pull
request for the updated packages.

AU/Plugins/PullRequest.ps1

@@ -0,0 +1,92 @@
+<#
+.SYNOPSIS
+    Creates a GitHub pull request for the updated packages.
+
+.DESCRIPTION
+    This plugin will open a GitHub pull request for the changes comitted by AU.
+    The plugin must be run only after the Git plugin is run. If no packages were updated,
+    no pull request will be created.
+#>
+param(
+    $Info,
+
+    # Git branch to create a GitHub pull request for
+    [string]$Branch,
+
+    # Target Git branch for the GitHub pull request
+    [string]$BaseBranch = "master",
+
+    # GitHub usernames to be added to the list of reviewers
+    [string[]]$Reviewers = @(),
+
+    # GitHub team slugs to be added to the list of reviewers
+    [string[]]$TeamReviewers = @(),
+
+    # GitHub usernames to be added to the list of assignees
+    [string[]]$Assignees = @(),
+
+    # GitHub API base url, overridable for GitHub Enterprise installations
+    [string]$GitHubAPI = "https://api.github.com",
+
+    # Github ApiKey, create in GitHub profile -> Settings -> Personal access tokens -> Generate new token
+    [string]$ApiKey
+)
+
+if ($Info.result.updated.Length -eq 0) { Write-Host "No package updated, skipping"; return }
+
+$ErrorActionPreference = "Stop"
+
+$origin = git config --get remote.origin.url
+$originParts = $origin -split {$_ -eq "/" -or $_ -eq ":"}
+$owner = $originParts[-2]
+$repo = $originParts[-1] -replace "\.git$", ""
+
+#https://github.com/majkinetor/au/issues/142
+if ($PSVersionTable.PSVersion.major -ge 6) {
+    $AvailableTls = [enum]::GetValues('Net.SecurityProtocolType') | Where-Object { $_ -ge 'Tls' } # PowerShell 6+ does not support SSL3, so use TLS minimum
+    $AvailableTls.ForEach({[Net.ServicePointManager]::SecurityProtocol = [Net.ServicePointManager]::SecurityProtocol -bor $_})
+} else {
+    [System.Net.ServicePointManager]::SecurityProtocol = 3072 -bor 768 -bor [System.Net.SecurityProtocolType]::Tls -bor [System.Net.SecurityProtocolType]::Ssl3
+}
+
+$data = @{
+    title = git log -1 --pretty="%s"
+    head = $Branch
+    base = $BaseBranch
+}
+$params = @{
+    ContentType = 'application/json'
+    Method = "POST"
+    Uri = "$GitHubAPI/repos/$owner/$repo/pulls"
+    Body = $data | ConvertTo-Json
+    UseBasicparsing = $true
+    Headers = @{
+        'Accept' = 'application/vnd.github.v3+json'
+        'Authorization' = ('Basic ' + [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes($ApiKey)))
+    }
+}
+$response = Invoke-WebRequest @params
+$jsonResponse = $response.Content | ConvertFrom-Json
+$prUrl = $jsonResponse.html_url
+$prNumber = $jsonResponse.number
+
+if ($Reviewers -or $TeamReviewers) {
+    $data = @{
+        reviewers = $Reviewers
+        team_reviewers = $TeamReviewers
+    }
+    $params['Uri'] = "$GitHubAPI/repos/$owner/$repo/pulls/$prNumber/requested_reviewers"
+    $params['Body'] = $data | ConvertTo-Json
+    $response = Invoke-WebRequest @params
+}
+
+if ($Assignees) {
+    $data = @{
+        assignees = $Assignees
+    }
+    $params['Uri'] = "$GitHubAPI/repos/$owner/$repo/issues/$prNumber/assignees"
+    $params['Body'] = $data | ConvertTo-Json
+    $response = Invoke-WebRequest @params
+}
+
+Write-Host "Pull request sucessfully created: $prUrl"