handle array root element

An array to string conversion notice was thrown when the root element of
the thing being validated is an array.
bug #10123 handle array root element (greg0ire)

This PR was submitted for the 2.4 branch but it was merged into the 2.3 branch instead (closes #10123).

Discussion
----------

handle array root element

An array to string conversion notice was thrown when the root element of the thing being validated is an array.

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

Commits
-------

17ed8bf handle array root element
Fixed ACE domain checks on UrlValidator (#10031)
bug #10275 [Validator] Fixed ACE domain checks on UrlValidator (#10031) (aeoris)

This PR was merged into the 2.3 branch.

Discussion
----------

[Validator] Fixed ACE domain checks on UrlValidator (#10031)

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #10031
| License       | MIT
| Doc PR        |

I added some checks to allow internationalised domain names as per reported on #10031 and some extra testcases to cover ACE domain names.

Commits
-------

7a2f154 Fixed ACE domain checks on UrlValidator (#10031)
Fix issue symfony/symfony#10345 '[FrameworkBundle][Console] container:debug --parameter="" not working anymore'
bug #10363 [FrameworkBundle][Console] Fix issue #10345 container:debug --parameter="" not working anymore (FineWolf)

This PR was merged into the 2.4 branch.

Discussion
----------

[FrameworkBundle][Console] Fix issue #10345 container:debug --parameter="" not working anymore

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes*
| Fixed tickets | #10345
| License       | MIT
| Doc PR        | N/A

## TODO
- [x] Fix issue #10345
- [ ] Create unit test for `describeContainerParameter`

Commits
-------

b278aa4 Fix issue symfony/symfony#10345 '[FrameworkBundle][Console] container:debug --parameter="" not working anymore'
Check headers sent before sending PHP response

If the response contents has been sent before an error occurs, PHP
triggers the warning "Cannot modify header information - headers already sent"

This change ensure that the error message is echoed, while it's impossible
to change the HTTP status code and headers.
bug #10523 [Debug] Check headers sent before sending PHP response (GromNaN)

This PR was merged into the 2.3 branch.

Discussion
----------

[Debug] Check headers sent before sending PHP response

If the response contents has been sent before an error occurs, PHP triggers the warning "Cannot modify header information - headers already sent".

This change ensure that the useful error message is echoed, while it's impossible to change the HTTP status code and headers.

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

Commits
-------

97591c1 Check headers sent before sending PHP response
Merge branch '2.3' into 2.4

* 2.3:
  Check headers sent before sending PHP response
  Fixed ACE domain checks on UrlValidator (#10031)
  handle array root element
Merge branch '2.4'

* 2.4:
  Check headers sent before sending PHP response
  Fix issue symfony/symfony#10345 '[FrameworkBundle][Console] container:debug --parameter="" not working anymore'
  Fixed ACE domain checks on UrlValidator (#10031)
  handle array root element