Bulk convert control files. (#19986)

```
function Convert-Control {
    Param($full)
    .\vcpkg.exe format-manifest $full
    $root = $full.Substring(0, $full.Length - 7) # CONTROL
    $new = $root + 'vcpkg.json'
    $content = Get-Content -Raw $new
    $asJson = ConvertFrom-Json $content -AsHashtable -Depth 100
    $oldVersion = $asJson['port-version']
    if ($null -eq $oldVersion) {
        $oldVersionFull = $asJson['version-string']
        Write-Host "Got version $oldVersionFull"
        $match = [System.Text.RegularExpressions.Regex]::Match($oldVersionFull, '^(.+)-(\d+)$')
        if ($match.Success -and -not [System.Text.RegularExpressions.Regex]::IsMatch($oldVersionFull, '^\d\d\d\d-\d\d-\d\d$')) {
            $newFullVersion = [string]$match.Groups[1].Value
            $oldVersion = [int]$match.Groups[2].Value
            Write-Host "newFullVersion $newFullVersion oldVersion $oldVersion"
            $newVersion = $oldVersion + 1
            $asJson['version-string'] = $newFullVersion
            Write-Host "Previous version for $full extracted from version field -- setting version-string $newFullVersion and port-version $newVersion"
        } else {
            Write-Host "No previous version for $full -- setting 1"
            $newVersion = 1
        }
    } else {
        $newVersion = [int]$oldVersion + 1
        Write-Host "New version for $full : $newVersion"
    }

    $asJson['port-version'] = $newVersion

    $content = ConvertTo-Json $asJson -Depth 100
    Set-Content -Path $new -Value $content
    .\vcpkg.exe format-manifest $new
}

Get-ChildItem ports\CONTROL -Recurse | Foreach-Object {
    Convert-Control $_.FullName
}

git commit -am "this message"
.\vcpkg.exe x-add-version -all
git commit -a --amend
```

2 files changed, 11 insertions, 5 deletions

diff --git a/ports/cppkafka/CONTROL b/ports/cppkafka/CONTROL
deleted file mode 100644
index 5dec433ef..000000000
--- a/ports/cppkafka/CONTROL
+++ /dev/null
@@ -1,5 +0,0 @@
-Source: cppkafka
-Version: 0.3.1-2
-Homepage: https://github.com/mfontanini/cppkafka
-Description: cppkafka allows C++ applications to consume and produce messages using the Apache Kafka protocol. The library is built on top of librdkafka, and provides a high level API that uses modern C++ features to make it easier to write code while keeping the wrapper's performance overhead to a minimum.
-Build-Depends: boost-program-options, librdkafka
diff --git a/ports/cppkafka/vcpkg.json b/ports/cppkafka/vcpkg.json
new file mode 100644
index 000000000..00473d972
--- /dev/null
+++ b/ports/cppkafka/vcpkg.json
@@ -0,0 +1,11 @@
+{
+  "name": "cppkafka",
+  "version-string": "0.3.1",
+  "port-version": 3,
+  "description": "cppkafka allows C++ applications to consume and produce messages using the Apache Kafka protocol. The library is built on top of librdkafka, and provides a high level API that uses modern C++ features to make it easier to write code while keeping the wrapper's performance overhead to a minimum.",
+  "homepage": "https://github.com/mfontanini/cppkafka",
+  "dependencies": [
+    "boost-program-options",
+    "librdkafka"
+  ]
+}