[Serializer] Add Support for object_to_populate in CustomNormalizer

[javiereguiluz]

symfony/symfony#21716

[javiereguiluz]

For someone who knows the Serializer component, this should be easy to document. Any volunteer? Thanks.

[Simperfit]

I'm going to document this.

[carsonbot]

Thank you for this issue.
There has not been a lot of activity here for a while. Has this been resolved?

[carsonbot]

Hello? This issue is about to be closed if nobody replies.

[carsonbot]

Hey,

I didn't hear anything so I'm going to close it. Feel free to comment if this is still relevant, I can always reopen!