Add only allowlist for connectors and requests

[craigpotter]

Overview of change

Adds an allowlist so users with many connectors/requests can record just a subset instead of maintaining an ever-growing ignore list:

// config/barstool.php
'only' => [
    'connectors' => [
        StripeConnector::class,
    ],
    'requests' => [],
],

Semantics

• If both only lists are empty (the default), everything is recorded — fully backward compatible, no config or migration changes needed for existing installs.
• If either list is non-empty, a request is recorded only when its connector class or request class is listed (exact class match, consistent with ignore).
• The ignore list is applied afterwards and always takes precedence, so you can allow a whole connector and still ignore individual noisy requests on it.

All three recording hooks (request, response, fatal) flow through shouldRecord(), so filtering behaves consistently everywhere.

Tidy-up

shouldRecord() was getting busy, so the checks are now extracted into named private methods — resolveClasses(), passesOnlyList(), passesIgnoreList() — keeping the method a short, readable conjunction. No public API changes.

Related

Closes #8

Testing

Six new Pest tests: only-connectors filtering, only-requests filtering, OR semantics across the two lists, ignore-beats-only (including the allow-connector/ignore-one-request case), conflict resolution when a class is in both lists, and the empty-lists backward-compatibility guard.

composer test (31 passed, 154 assertions), composer analyse (PHPStan level 8, clean), composer format (clean).