feat(http-client-python): add mock API tests for payload/head scenario

[Copilot]

Adds Python SDK mock API tests for the payload/head Spector scenario introduced in #10194 — a HEAD operation returning Content-Type and x-ms-meta response headers with no body.

Changes

• package.json — Bumps @typespec/http-specs to 0.1.0-alpha.37 (stable version containing the payload/head spec)
• mock_api/shared/test_payload_head.py + asynctests/test_payload_head_async.py — Sync and async tests placed in shared/ since both azure and unbranded flavors expose identical import paths and API surface

The tests cover two scenarios:

def test_content_type_header_in_response(client: HeadClient):
    assert client.content_type_header_in_response() is True

def test_content_type_header_in_response_with_cls(client: HeadClient):
    headers = client.content_type_header_in_response(cls=lambda x, y, z: z)
    assert headers["Content-Type"] == "text/plain; charset=utf-8"
    assert headers["x-ms-meta"] == "hello"

The scenario sends a HEAD request to /payload/head/content-type-header-in-response and expects a 200 response with Content-Type: text/plain; charset=utf-8 and x-ms-meta: hello headers. The cls variant verifies that response headers are correctly deserialized and accessible via the callback.

[msyyc]

@copilot resolve the merge conflicts in this pull request

[Copilot]

@copilot resolve the merge conflicts in this pull request

Resolved. The conflicts in package.json and package-lock.json have been fixed by taking main's ~0.82.0 versions for @typespec/sse/streams/xml and using the stable @typespec/http-specs@0.1.0-alpha.37 (which already includes the payload/head spec). The branch is now merged with main.

[msyyc]

@copilot resolve the merge conflicts in this pull request

[Copilot]

@copilot resolve the merge conflicts in this pull request

Resolved in 119ab0ac. The only conflict was in package-lock.json, which I regenerated from main's base via npm install.

[msyyc]

move to #10944