Improve the Code BC guide

[yceruto]

https://symfony.com/doc/current/contributing/code/bc.html#working-on-symfony-code

Currently we can know (in terms of BC) what is not allowed to do and why, but we are omitting that some BC breaks could be avoided with alternative solutions. For instance: symfony/symfony#33003 (comment)

I've two proposals to improve that:

1. Add an example code + explanation where it's possible make the changes avoiding the "BC break", so contributors will know how to do it correctly. I can help to find in the codebase the workaround for each case.
2. Add a permanent link to each BC topic, so we can easily share them.

WDYT?

[carsonbot]

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

[carsonbot]

Could I get a reply or should I close this?

[yceruto]

let's close since there is no interest or this is something that cannot be achieved in a short term.