feat: Begin working on configuration client.

Sources/CliClient/Internal/Template.swift

@@ -0,0 +1,30 @@
+@_spi(Internal)
+public struct Template: Sendable {
+  let type: TemplateType
+  let version: String?
+
+  enum TemplateType: String, Sendable {
+    case optionalString = "String?"
+    case string = "String"
+  }
+
+  var value: String {
+    let versionString = version != nil ? "\"\(version!)\"" : "nil"
+    return """
+    // Do not set this variable, it is set during the build process.
+    let VERSION: \(type.rawValue) = \(versionString)
+    """
+  }
+
+  public static func build(_ version: String? = nil) -> String {
+    nonOptional(version)
+  }
+
+  public static func nonOptional(_ version: String? = nil) -> String {
+    Self(type: .string, version: version).value
+  }
+
+  public static func optional(_ version: String? = nil) -> String {
+    Self(type: .optionalString, version: version).value
+  }
+}