[FrameworkBundle] Add sid_length and sid_bits_per_character session ini options in configuration

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #29830
| License       | MIT
| Doc PR        | n/a

this a fix for the issue #29830

After deliberation, we estimate that only `sid_length` and` sid_bits_per_character` session options should be exposed. These options à optional.

For others, we recommend changing your php.ini file

We can now configure the session like this :

```yaml
framwork:
  session:
    sid_length: 64 //optional, recommended value is 32
    sid_bits_per_character: 6 //optional, recommended value is 5
```

src/Symfony/Bundle/FrameworkBundle/CHANGELOG.md

@@ -13,6 +13,8 @@ CHANGELOG
    original serialization method, set the `framework.messenger.serializer.id`
    config option to `messenger.transport.symfony_serializer`.
  * Added information about deprecated aliases in `debug:autowiring` 
+ * Added php ini session options `sid_length` and `sid_bits_per_character` 
+   to the `session` section of the configuration
 
 4.2.0
 -----

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php

@@ -509,6 +509,14 @@ class Configuration implements ConfigurationInterface
                             ->defaultValue(0)
                             ->info('seconds to wait between 2 session metadata updates')
                         ->end()
+                        ->integerNode('sid_length')
+                            ->min(22)
+                            ->max(256)
+                        ->end()
+                        ->integerNode('sid_bits_per_character')
+                            ->min(4)
+                            ->max(6)
+                        ->end()
                     ->end()
                 ->end()
             ->end()

src/Symfony/Bundle/FrameworkBundle/Resources/config/schema/symfony-1.0.xsd

@@ -112,6 +112,8 @@
         <xsd:attribute name="gc-probability" type="xsd:string" />
         <xsd:attribute name="save-path" type="xsd:string" />
         <xsd:attribute name="metadata-update-threshold" type="xsd:nonNegativeInteger" />
+        <xsd:attribute name="sid-length" type="sid_length" />
+        <xsd:attribute name="sid-bits-per-character" type="sid_bits_per_character" />
     </xsd:complexType>
 
     <xsd:complexType name="request">
@@ -343,7 +345,7 @@
         </xsd:restriction>
     </xsd:simpleType>
 
-     <xsd:simpleType name="cookie_samesite">
+    <xsd:simpleType name="cookie_samesite">
         <xsd:restriction base="xsd:string">
             <xsd:enumeration value="" />
             <xsd:enumeration value="lax" />
@@ -351,6 +353,21 @@
         </xsd:restriction>
     </xsd:simpleType>
 
+    <xsd:simpleType name="sid_bits_per_character">
+        <xsd:restriction base="xsd:positiveInteger">
+            <xsd:enumeration value="4" />
+            <xsd:enumeration value="5" />
+            <xsd:enumeration value="6" />
+        </xsd:restriction>
+    </xsd:simpleType>
+
+    <xsd:simpleType name="sid_length">
+        <xsd:restriction base="xsd:positiveInteger">
+            <xsd:minInclusive value="22" />
+            <xsd:maxInclusive value="256" />
+        </xsd:restriction>
+    </xsd:simpleType>
+
     <xsd:simpleType name="workflow_type">
         <xsd:restriction base="xsd:string">
             <xsd:enumeration value="state_machine" />