Add HTTPX hook access to request and response objects

[Harshal96]

Description

Add access to the original httpx.Request and httpx.Response objects from HTTPX request and response hook info while preserving the existing tuple fields. This lets hooks read request content and call response.response.read() or response.response.aread() so HTTPX caches response bodies for later application use.

Fixes #2556

Type of change

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

How Has This Been Tested?

• uv run --no-sync --with tox tox -e py312-test-instrumentation-httpx-1-wrapt2
• uv run --no-sync --with tox tox -e py312-test-instrumentation-httpx-0-wrapt2
• uv run --no-sync --with tox tox -e lint-instrumentation-httpx
• uv run --no-sync --with pre-commit pre-commit run ruff --files instrumentation/opentelemetry-instrumentation-httpx/src/opentelemetry/instrumentation/httpx/__init__.py instrumentation/opentelemetry-instrumentation-httpx/tests/test_httpx_integration.py instrumentation/opentelemetry-instrumentation-httpx/README.rst
• uv run --no-sync --with pre-commit pre-commit run ruff-format --files instrumentation/opentelemetry-instrumentation-httpx/src/opentelemetry/instrumentation/httpx/__init__.py instrumentation/opentelemetry-instrumentation-httpx/tests/test_httpx_integration.py
• uv run --no-sync --with pre-commit pre-commit run rstcheck --files instrumentation/opentelemetry-instrumentation-httpx/README.rst

Does This PR Require a Core Repo Change?

• No.

Checklist:

See contributing.md for styleguide, changelog guidelines, and more.

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[emdneto]

Thanks for the PR!

Just a heads-up: we no longer update CHANGELOG.md directly. The changelog is now generated from changelog fragments using Towncrier.

Please add the appropriate changelog fragment for this change instead of editing CHANGELOG.md manually. You can find the instructions and expected format in CONTRIBUTING.md.

[Harshal96]

Done!