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, 28 insertions, 18 deletions

diff --git a/ports/mongo-cxx-driver/CONTROL b/ports/mongo-cxx-driver/CONTROL
deleted file mode 100644
index c7b22bef1..000000000
--- a/ports/mongo-cxx-driver/CONTROL
+++ /dev/null
@@ -1,18 +0,0 @@
-Source: mongo-cxx-driver
-Version: 3.4.0-5
-Port-Version: 2
-Build-Depends: libbson, mongo-c-driver, boost-smart-ptr, boost-optional, boost-utility
-Homepage: https://github.com/mongodb/mongo-cxx-driver
-Description: MongoDB C++ Driver.
-
-Feature: mnmlstc
-Description: Use MNMLSTC/core C++17 polyfill.
-
-Feature: system-mnmlstc
-Description: Use an available version of MNMLSTC on your system as C++17 polyfill.
-
-Feature: boost
-Description: Use Boost C++17 polyfill. The only option under MSVC.
-
-Feature: std-experimental
-Description: Use optional and string_view from std::experimental.
diff --git a/ports/mongo-cxx-driver/vcpkg.json b/ports/mongo-cxx-driver/vcpkg.json
new file mode 100644
index 000000000..60e374eba
--- /dev/null
+++ b/ports/mongo-cxx-driver/vcpkg.json
@@ -0,0 +1,28 @@
+{
+  "name": "mongo-cxx-driver",
+  "version-string": "3.4.0-5",
+  "port-version": 3,
+  "description": "MongoDB C++ Driver.",
+  "homepage": "https://github.com/mongodb/mongo-cxx-driver",
+  "dependencies": [
+    "boost-optional",
+    "boost-smart-ptr",
+    "boost-utility",
+    "libbson",
+    "mongo-c-driver"
+  ],
+  "features": {
+    "boost": {
+      "description": "Use Boost C++17 polyfill. The only option under MSVC."
+    },
+    "mnmlstc": {
+      "description": "Use MNMLSTC/core C++17 polyfill."
+    },
+    "std-experimental": {
+      "description": "Use optional and string_view from std::experimental."
+    },
+    "system-mnmlstc": {
+      "description": "Use an available version of MNMLSTC on your system as C++17 polyfill."
+    }
+  }
+}