Introducing the QueryBuildingMode Enum to improve serialization

[nyamsprod]

Enum were introduced in PHP8.1 see https://wiki.php.net/rfc/enumerations#serialization but nothing was said about their serialization with http_build_query. This resulted on Enum using the same serialization as other object ie relying on the results of get_object_vars.

In PHP8.4 Enum representation was updated to match Enum representation with json_encode. This introduced a couple of changes:

• http_build_query can serialise BackedEnum using their value;
• http_build_query can not serialise UnitEnum and will throw a TypeError
• UnitEnum can not be use as input for the first argument of http_build_query which will result also in a TypeError.

To allow migrating your code from pre-PHP8.4 this PR introduces an Enum:

enum QueryBuildingMode
{
    /**
     * Use current http_build_query algorithm.
     */
    case Native;

    /**
     * Strictly uses get_object_vars on objects (Enum included)
     * if the value can not be serialized the entry is skipped.
     *
     * ie http_build_query behavior before PHP8.4
     */
    case Compatible;

    /**
     * Mimic PHP8.4+ http_build_query behavior
     * with support for Enum
     */
    case EnumNative;

    /**
     * Validation-first mode.
     *
     * Guarantees that only scalar values, backed Enum and null are accepted.
     * Any object, Pure Enum, resource, or recursive structure
     * results in an exception.
     *
     * This contract is stable and independent of PHP's
     * http_build_query implementation.
     */
    case Strict;
}

And improve QueryString::compose and QueryString::composeFromValue as well as Query object related methods that currently uses only http_build_query.

enum Backed: string
{
    case One = 'Un';
    case Two = 'Deux';
}

$params = ['bar' => Backed::One, 'baz' => 1];

echo QueryString::compose($params, queryBuildingMode: QueryBuildingMode::Native);
// in PHP8.4+ returns "bar=Un&baz=1"
// in PHP8.4- returns "bar%5Bname%5D=One&bar%5Bvalue%5D=Un&baz=1"

echo QueryString::compose($params, queryBuildingMode: QueryBuildingMode::Compatible);
// returns  "bar%5Bname%5D=One&bar%5Bvalue%5D=Un&baz=1" regardless of PHP version

echo QueryString::compose($params, queryBuildingMode: QueryBuildingMode::EnumNative);
// returns "bar=Un&baz=1" regardless of PHP version

echo QueryString::compose($params, queryBuildingMode: QueryBuildingMode::Strict);
// returns "bar=Un&baz=1" regardless of PHP version