[LiveComponent] Prevent __component property to be serialized when called JSON.stringify()

[Kocal]

Q	A
Bug fix?	yes
New feature?	no
Issues	Fix #...
License	MIT

Following https://symfony-devs.slack.com/archives/C01FN4EQNLX/p1738238525455439

With some RUM tools that listen user interactions, some of them can JSON.stringify() their payload. But if their payload contains an HTML element with the property __component (which represents a Proxy to the LiveComponent instance), then it tries to be serialized and lead to an error by trying to call an action toJSON and trigger an XHR request to /toJSON:

Let's change the property assignment with Object.defineProperty(), so the property is not enumarable and so not serialized when JSON.stringify() is called:

cc @jwage

[github-actions]

📊 Packages dist files size difference

Thanks for the PR! Here is the difference in size of the packages dist files between the base branch and the PR.
Please review the changes and make sure they are expected.

File	Before (Size / Gzip)	After (Size / Gzip)
LiveComponent
live_controller.js	119.92 kB / 23.37 kB	120 kB0% / 23.4 kB0%

[smnandre]

Thank you @jwage for the time spent to assist / explain what happened.

@Kocal 🙇 you'be been a legend today

[kbond]

Wow, that was a deep dive!

[Kocal]

(Added missing changelog)