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, 48 insertions, 29 deletions

diff --git a/ports/rocksdb/CONTROL b/ports/rocksdb/CONTROL
deleted file mode 100644
index b63c6774e..000000000
--- a/ports/rocksdb/CONTROL
+++ /dev/null
@@ -1,29 +0,0 @@
-Source: rocksdb
-Version: 6.14.6
-Homepage: https://github.com/facebook/rocksdb
-Description: A library that provides an embeddable, persistent key-value store for fast storage
-Default-Features: zlib
-
-Feature: lz4
-Build-Depends: lz4
-Description: lz4 support in rocksdb
-
-Feature: snappy
-Build-Depends: snappy
-Description: snappy support in rocksdb
-
-Feature: zlib
-Build-Depends: zlib
-Description: zlib support in rocksdb
-
-Feature: tbb
-Build-Depends: tbb
-Description: tbb support in rocksdb
-
-Feature: zstd
-Build-Depends: zstd
-Description: zstd support in rocksdb
-
-Feature: bzip2
-Build-Depends: bzip2
-Description: bzip2 support in rocksdb
diff --git a/ports/rocksdb/vcpkg.json b/ports/rocksdb/vcpkg.json
new file mode 100644
index 000000000..d1c4940f8
--- /dev/null
+++ b/ports/rocksdb/vcpkg.json
@@ -0,0 +1,48 @@
+{
+  "name": "rocksdb",
+  "version-string": "6.14.6",
+  "port-version": 1,
+  "description": "A library that provides an embeddable, persistent key-value store for fast storage",
+  "homepage": "https://github.com/facebook/rocksdb",
+  "default-features": [
+    "zlib"
+  ],
+  "features": {
+    "bzip2": {
+      "description": "bzip2 support in rocksdb",
+      "dependencies": [
+        "bzip2"
+      ]
+    },
+    "lz4": {
+      "description": "lz4 support in rocksdb",
+      "dependencies": [
+        "lz4"
+      ]
+    },
+    "snappy": {
+      "description": "snappy support in rocksdb",
+      "dependencies": [
+        "snappy"
+      ]
+    },
+    "tbb": {
+      "description": "tbb support in rocksdb",
+      "dependencies": [
+        "tbb"
+      ]
+    },
+    "zlib": {
+      "description": "zlib support in rocksdb",
+      "dependencies": [
+        "zlib"
+      ]
+    },
+    "zstd": {
+      "description": "zstd support in rocksdb",
+      "dependencies": [
+        "zstd"
+      ]
+    }
+  }
+}