feat: HTTP preconnect feature minimal for electronjs (#19952)

* feat: HTTP preconnect feature minimal for electronjs

* fix type of PreconnectRequest::PreconnectRequest impl

* roll back past https://chromium-review.googlesource.com/c/chromium/src/+/1713306

* mark docs as experimental

* fix lint

docs/api/session.md

@@ -91,6 +91,20 @@ session.defaultSession.on('will-download', (event, item, webContents) => {
 })
 ```
 
+#### Event: 'preconnect' _Experimental_
+
+Returns:
+
+* `event` Event
+* `preconnectUrl` String - The URL being requested for preconnection by the
+  renderer.
+* `allowCredentials` Boolean - True if the renderer is requesting that the
+  connection include credentials (see the
+  [spec](https://w3c.github.io/resource-hints/#preconnect) for more details.)
+
+Emitted when a render process requests preconnection to a URL, generally due to
+a [resource hint](https://w3c.github.io/resource-hints/).
+
 ### Instance Methods
 
 The following methods are available on instances of `Session`:
@@ -238,6 +252,14 @@ window.webContents.session.enableNetworkEmulation({
 window.webContents.session.enableNetworkEmulation({ offline: true })
 ```
 
+#### `ses.preconnect(options)` _Experimental_
+
+* `options` Object
+  * `url` String - URL for preconnect. Only the origin is relevant for opening the socket.
+  * `numSockets` Number (optional) - number of sockets to preconnect. Must be between 1 and 6. Defaults to 1.
+
+Preconnects the given number of sockets to an origin.
+
 #### `ses.disableNetworkEmulation()`
 
 Disables any network emulation already active for the `session`. Resets to