refactor(tests): build the e2e client on utopia-php/client

[ChiragAgg5k]

Summary

utopia-php/fetch is archived. The executor's own code already uses utopia-php/client ^0.6, and fetch was left only as a dev dependency for tests/e2e/Client.php. That class extends Utopia\Fetch\Client, and appwrite-labs/edge reuses it (through vendor/open-runtimes/executor/tests/e2e) for its executor E2E suite. Edge has to keep fetch too until this changes.

This rewrites the test client on utopia-php/client (cURL adapter) and drops utopia-php/fetch from require-dev. The lock loses only utopia-php/fetch 1.1.2.

The public surface is unchanged, because Edge's K8sExecutorClient extends this class and uses self::METHOD_POST:

• __construct(string $endpoint, array $baseHeaders = []), setKey().
• call(...) with the same signature and return shape (headers with lowercased names plus status-code, body).
• METHOD_GET/POST/PUT/PATCH/DELETE/HEAD/OPTIONS constants. They are now declared here instead of inherited, and the values are the same strings.
• It no longer extends a client class. Nothing in this repository or in Edge calls an inherited fetch method on it.

fetch's request semantics are kept on purpose, since several tests depend on them:

• No Accept header is added. The accept-header tests send their own, and psr7's json() helper would have added application/json, so the body is built with json_encode directly.
• GET parameters use http_build_query's default encoding (+ for spaces), as fetch did, not psr7's RFC 3986 query().
• Bodies are JSON, form-encoded or multipart by the request's content type. Multipart params are flattened to parent[child] fields with null as an empty field, as fetch handed them to curl, and the request carries the factory's multipart/form-data; boundary=… content type, which libcurl used to add. An unknown content type with a non-empty body throws instead of guessing.
• Up to 5 redirects are followed, the connect timeout is 5s, and the $timeout argument stays in milliseconds.
• Response headers are lowercased, and the last value of a repeated header wins, as fetch's header callback did.
• With a $callback, chunks are streamed through Client::stream() and body is null.

One wire difference: the client asks for compressed responses (Accept-Encoding) and decodes them. fetch sent no Accept-Encoding. Bodies come back identical. On a compressed response, content-encoding and content-length are dropped from the returned headers. No test here or in Edge asserts on them, and the executor doesn't compress its responses.

Part of appwrite/appwrite#13828. Once this is released, Edge bumps to it and drops fetch entirely.

Tests

• composer format:check, composer analyze, composer refactor:check and composer test:unit (37 tests) all pass.
• A smoke run against a local PHP echo server matched fetch's behaviour on these cases:
  • GET query encoding;
  • the JSON POST body;
  • a DELETE with an empty params array sending [];
  • a multipart request with flattened nested fields, true as 1 and null as an empty field;
  • Accept: */* (curl's default) left untouched;
  • the bearer token;
  • repeated-header handling;
  • streamed chunks.
• The E2E suite (82 call() sites, including multipart responses and log streaming) runs in CI.