…eference arguments in collection arguments (ogizanagi)

This PR was merged into the 3.1-dev branch.

Discussion
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[DependencyInjection] Properly ignore invalid reference arguments in collection arguments

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

With this new feature, the following configuration:

```xml
<service id="baz" class="Baz"/>

<service id="foo" class="Foo">
    <argument type="collection">
        <argument type="service" id="bar" on-invalid="ignore" />
        <argument type="service" id="baz" />
        <argument type="service" id="moo" on-invalid="null" />
    </argument>

    <argument type="service" id="bar" on-invalid="ignore" />
    <argument type="service" id="baz" />
    <argument type="service" id="moo" on-invalid="null" />

    <call method="foo">
        <argument type="service" id="bar" on-invalid="ignore" />
    </call>
    <call method="fooCollection">
        <argument type="collection">
            <argument type="service" id="bar" on-invalid="ignore" />
            <argument type="service" id="baz" />
            <argument type="service" id="moo" on-invalid="null" />
        </argument>
    </call>
</service>
```

will result into the following `Definition`:

```php
Definition {#64 ▼
  -class: "Foo"
  // […]
  -calls: array:1 [▼
    0 => array:2 [▼
      0 => "fooCollection"
      1 => array:1 [▼
        0 => array:2 [▼
          0 => Reference {#59 ▼
            -id: "baz"
            -invalidBehavior: 1
          }
          1 => null
        ]
      ]
    ]
  ]
  // […]
  #arguments: array:4 [▼
    0 => array:2 [▼
      0 => Reference {#63 ▼
        -id: "baz"
        -invalidBehavior: 1
      }
      1 => null
    ]
    1 => null
    2 => Reference {#56 ▼
      -id: "baz"
      -invalidBehavior: 1
    }
    3 => null
  ]
}
```

Invalid references are ignored instead of replaced by `null` when they are part of a collection argument.
If the collection argument is part of a method call and contains an invalid reference, the method call is kept, but the invalid reference removed.

The behavior stays the same as before for non-collection arguments.

:christmas_tree:

Commits
-------

cfc4879 [DependencyInjection] Properly ignore invalid reference arguments in collection arguments