[HttpFoundation] Add a way to avoid the session be written at each request
[HttpFoundation] added a way to override the Request class
feature#8957 [HttpFoundation] added a way to override the Request class (fabpot)

This PR was merged into the master branch.

Discussion
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[HttpFoundation] added a way to override the Request class

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #7461, #7453
| License       | MIT
| Doc PR        | symfony/symfony-docs#3021

This is an alternative implementation for #7461.

I've also reverted #7381 and #7390 as these changes are not needed anymore.

Todo:

 - [ ] add some tests

Commits
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464439d [HttpFoundation] added a way to override the Request class
fixed test side effects