refactor: implement ipcRenderer.sendTo in native code for better performance

[miniak]

Description of Change

ipcRenderer.sendTo currently sends an internal ELECTRON_BROWSER_SEND_TO message, which is handled by rpc-server.js. This leads to unnecessary native <-> V8 value conversions as the message is forwarded to the target renderer. This PR moves the forwarding to the native code to avoid this overhead.

Tested by sending an IPC with 10 MB buffer to a different renderer and then back + measuring the time it takes for the message to come back:

• before 480 ms
• after 420 ms

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• PR title follows semantic commit guidelines

Release Notes

Notes: ipcRenderer.sendTo performance improved by implementing forwarding in native code

[deepak1556]

LGTM 👍

[release-clerk]

Release Notes Persisted

ipcRenderer.sendTo performance improved by implementing forwarding in native code

[bpasero]

@miniak just wondering, is ipcRenderer.sendTo going to the main process first and then to the renderer or is it a true renderer <=> renderer communication?

[miniak]

@bpasero I would like to get there eventually, but that’s way more complicated.

[bpasero]

@miniak ok good to know, thanks for clarifying