schema: add Schema::unwrap_*_schema_cloned

This way we can copy and modify a schema.

Eg. via the following ways:

    const FOO_SCHEMA: Schema = SOME_SCHEMA
        .unwrap_integer_schema_cloned()
        .description("Foo")
        .schema();

Note that for example there is currently no builder to set a
`default_key` for an `ObjectSchema` back to None, so one could do:

    const FOO_SCHEMA: Schema = const {
        let mut schema = SOME_SCHEMA.unwrap_object_schema_cloned();
        schema.default_key = None;
        schema.schema()
    };

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

proxmox-schema/src/schema.rs

@@ -1456,6 +1456,70 @@ impl Schema {
             _ => None,
         }
     }
+
+    /// Gets a copy of the underlying [`BooleanSchema`], panics on different schemas.
+    pub const fn unwrap_boolean_schema_cloned(&self) -> BooleanSchema {
+        match self {
+            Schema::Boolean(s) => BooleanSchema { ..*s },
+            _ => panic!("unwrap_boolean_schema_cloned on different schema"),
+        }
+    }
+
+    /// Gets a copy of the underlying [`IntegerSchema`], panics on different schemas.
+    pub const fn unwrap_integer_schema_cloned(&self) -> IntegerSchema {
+        match self {
+            Schema::Integer(s) => IntegerSchema { ..*s },
+            _ => panic!("unwrap_integer_schema_cloned on different schema"),
+        }
+    }
+
+    /// Gets a copy of the underlying [`NumberSchema`], panics on different schemas.
+    pub const fn unwrap_number_schema_cloned(&self) -> NumberSchema {
+        match self {
+            Schema::Number(s) => NumberSchema { ..*s },
+            _ => panic!("unwrap_number_schema_cloned on different schema"),
+        }
+    }
+
+    /// Gets the underlying [`StringSchema`], panics on different schemas.
+    pub const fn unwrap_string_schema_cloned(&self) -> StringSchema {
+        match self {
+            Schema::String(s) => StringSchema { ..*s },
+            _ => panic!("unwrap_string_schema_cloned on different schema"),
+        }
+    }
+
+    /// Gets the underlying [`ObjectSchema`], panics on different schemas.
+    pub const fn unwrap_object_schema_cloned(&self) -> ObjectSchema {
+        match self {
+            Schema::Object(s) => ObjectSchema { ..*s },
+            _ => panic!("unwrap_object_schema_cloned on different schema"),
+        }
+    }
+
+    /// Gets the underlying [`ArraySchema`], panics on different schemas.
+    pub const fn unwrap_array_schema_cloned(&self) -> ArraySchema {
+        match self {
+            Schema::Array(s) => ArraySchema { ..*s },
+            _ => panic!("unwrap_array_schema_cloned on different schema"),
+        }
+    }
+
+    /// Gets the underlying [`AllOfSchema`], panics on different schemas.
+    pub const fn unwrap_all_of_schema_cloned(&self) -> AllOfSchema {
+        match self {
+            Schema::AllOf(s) => AllOfSchema { ..*s },
+            _ => panic!("unwrap_all_of_schema_cloned on different schema"),
+        }
+    }
+
+    /// Gets the underlying [`OneOfSchema`], panics on different schemas.
+    pub const fn unwrap_one_of_schema_cloned(&self) -> OneOfSchema {
+        match self {
+            Schema::OneOf(s) => OneOfSchema { ..*s },
+            _ => panic!("unwrap_one_of_schema_cloned on different schema"),
+        }
+    }
 }
 
 /// A string enum entry. An enum entry must have a value and a description.