Container::camelize also takes backslashes into consideration
bug #9610 Container::camelize also takes backslashes into consideration (ondrejmirtes)

This PR was submitted for the 2.4 branch but it was merged into the 2.3 branch instead (closes #9610).

Discussion
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Container::camelize also takes backslashes into consideration

I [complained](https://github.com/symfony/symfony/pull/8494) about unreported and unnoticed BC break.

Service names in our DI container contain backslashes and that pull request rendered newer versions of Symfony unusable for us.

This commit fixes this - it normalizes backslashes in service names into underscores.

Commits
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0f9bb0a Container::camelize also takes backslashes into consideration