[HttpFoundation] Remove content-related headers if content is empty
bug #11244 [HttpFoundation] Remove body-related headers when sending the response, if body is empty (SimonSimCity)

This PR was submitted for the master branch but it was merged into the 2.3 branch instead (closes #11244).

Discussion
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[HttpFoundation] Remove body-related headers when sending the response, if body is empty

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

I've updated the implementation for informational and 204 or 304 responses. They will now, as they have no content, not return headers like `content-type` or `content-length`.

I'm unsure about `content-length` - we could also set it hardcoded to zero ... but I thought, that (because the specs say that it just can't have a response-body) the system should not return anything here.

Commits
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9dbe89d [HttpFoundation] Remove content-related headers if content is empty
fixed CS
[2.3][Form] Cleanup & fix phpdocs
[Upgrade] Fixed markdown syntax
minor #11359 [Upgrade] Fixed markdown syntax (lyrixx)

This PR was merged into the 2.3 branch.

Discussion
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[Upgrade] Fixed markdown syntax

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | N/A
| License       | MIT
| Doc PR        |

Commits
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deb70c7 [Upgrade] Fixed markdown syntax
[HttpFoundation] Fix wrong assertion in Response test
minor #11358 [2.3][Form] Cleanup & fix phpdocs (stloyd)

This PR was merged into the 2.3 branch.

Discussion
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[2.3][Form] Cleanup & fix phpdocs

| Q             | A
| ------------- | ---
| Bug fix?      | kinda
| New feature?  | no
| BC breaks?    | no
| Tests pass?   | yes
| License       | MIT

This PR was done mostly cause of reports about invalid/not supported types/variables in phpstorm/scrutinizer-ci, and after I started fixing I noticed more problems in those phpdocs so I have cleanedup them a bit.

Commits
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a67bc76 [2.3][Form] Cleanup & fix phpdocs
fix issue #8171 on configuration tree for twig extension -- pairing up with @cordoval
added regression test
bug #9719 [TwigBundle] fix configuration tree for paths (mdavis1982, cordoval)

This PR was submitted for the master branch but it was merged into the 2.3 branch instead (closes #9719).

Discussion
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[TwigBundle] fix configuration tree for paths

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #8171
| License       | MIT
| Doc PR        | na

This is a joint effort with @mdavis1982 and @cordoval :baby: pairing up and warming for hacking day in Warsaw

Commits
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9aa88e4 added regression test
4201d41 fix issue #8171 on configuration tree for twig extension -- pairing up with @cordoval
minor #11362 [2.3][HttpFoundation] Fix wrong assertion in Response test (stloyd)

This PR was merged into the 2.3 branch.

Discussion
----------

[2.3][HttpFoundation] Fix wrong assertion in Response test

| Q             | A
| ------------- | ---
| Bug fix?      | kinda
| New feature?  | no
| BC breaks?    | no
| Tests pass?   | yes
| License       | MIT

Commits
-------

3d63f80 [HttpFoundation] Fix wrong assertion in Response test
fixed typo