feat(NODE-5189): deprecate tcp keepalive options (#3621)

Author: durran

src/cmap/connection.ts

@@ -122,7 +122,9 @@ export interface ConnectionOptions
   credentials?: MongoCredentials;
   connectTimeoutMS?: number;
   tls: boolean;
+  /** @deprecated - Will not be able to turn off in the future. */
   keepAlive?: boolean;
+  /** @deprecated - Will not be configurable in the future. */
   keepAliveInitialDelay?: number;
   noDelay?: boolean;
   socketTimeoutMS?: number;

src/connection_string.ts

@@ -852,11 +852,13 @@ export const OPTIONS = {
   },
   keepAlive: {
     default: true,
-    type: 'boolean'
+    type: 'boolean',
+    deprecated: 'Will not be able to turn off in the future.'
   },
   keepAliveInitialDelay: {
     default: 120000,
-    type: 'uint'
+    type: 'uint',
+    deprecated: 'Will not be configurable in the future.'
   },
   loadBalanced: {
     default: false,

src/mongo_client.ts

@@ -212,9 +212,12 @@ export interface MongoClientOptions extends BSONSerializeOptions, SupportedNodeC
   sslCRL?: string;
   /** TCP Connection no delay */
   noDelay?: boolean;
-  /** TCP Connection keep alive enabled */
+  /** @deprecated TCP Connection keep alive enabled. Will not be able to turn off in the future. */
   keepAlive?: boolean;
-  /** The number of milliseconds to wait before initiating keepAlive on the TCP socket */
+  /**
+   * @deprecated The number of milliseconds to wait before initiating keepAlive on the TCP socket.
+   *             Will not be configurable in the future.
+   */
   keepAliveInitialDelay?: number;
   /** Force server to assign `_id` values instead of driver */
   forceServerObjectId?: boolean;