Feature/httpx2 instrumentor (#4730)

* httpx2 instrumentation support

* small readme edit

* Add docstring for httpx2

* doc updates

* ensure that if only httpx2 is available, that the httpx instrumentor isn't backed by httpx2 classes

* feedback: httpx protocol to type checking block

* feedback: remove top level fail, fix annotations

* feedback: move class definitions to the same conditions, fix docgen and genned workflows

* feedback: pull out the client instrumentor

* tox -e generate

---------

Co-authored-by: Riccardo Magliocchetti <riccardo.magliocchetti@gmail.com>

Author: gloshkajian

.changelog/4730.added

@@ -0,0 +1 @@
+`opentelemetry-instrumentation-httpx`: add support for httpx2

.github/workflows/core_contrib_test.yml

@@ -3087,6 +3087,126 @@ jobs:
       - name: Run tests
         run: tox -e py310-test-instrumentation-httpx-1-wrapt2 -- -ra
 
+  py310-test-instrumentation-httpx-2-wrapt1:
+    name: instrumentation-httpx-2-wrapt1 
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    steps:
+      - name: Checkout contrib repo @ SHA - ${{ env.CONTRIB_REPO_SHA }}
+        uses: actions/checkout@v4
+        with:
+          repository: open-telemetry/opentelemetry-python-contrib
+          ref: ${{ env.CONTRIB_REPO_SHA }}
+
+      - name: Checkout core repo @ SHA - ${{ env.CORE_REPO_SHA }}
+        uses: actions/checkout@v4
+        with:
+          repository: open-telemetry/opentelemetry-python
+          ref: ${{ env.CORE_REPO_SHA }}
+          path: opentelemetry-python
+
+      - name: Set up Python 3.10
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.10"
+          architecture: "x64"
+
+      - name: Install tox
+        run: pip install tox-uv
+
+      - name: Run tests
+        run: tox -e py310-test-instrumentation-httpx-2-wrapt1 -- -ra
+
+  py310-test-instrumentation-httpx-2-wrapt2:
+    name: instrumentation-httpx-2-wrapt2 
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    steps:
+      - name: Checkout contrib repo @ SHA - ${{ env.CONTRIB_REPO_SHA }}
+        uses: actions/checkout@v4
+        with:
+          repository: open-telemetry/opentelemetry-python-contrib
+          ref: ${{ env.CONTRIB_REPO_SHA }}
+
+      - name: Checkout core repo @ SHA - ${{ env.CORE_REPO_SHA }}
+        uses: actions/checkout@v4
+        with:
+          repository: open-telemetry/opentelemetry-python
+          ref: ${{ env.CORE_REPO_SHA }}
+          path: opentelemetry-python
+
+      - name: Set up Python 3.10
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.10"
+          architecture: "x64"
+
+      - name: Install tox
+        run: pip install tox-uv
+
+      - name: Run tests
+        run: tox -e py310-test-instrumentation-httpx-2-wrapt2 -- -ra
+
+  py310-test-instrumentation-httpx-3-wrapt1:
+    name: instrumentation-httpx-3-wrapt1 
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    steps:
+      - name: Checkout contrib repo @ SHA - ${{ env.CONTRIB_REPO_SHA }}
+        uses: actions/checkout@v4
+        with:
+          repository: open-telemetry/opentelemetry-python-contrib
+          ref: ${{ env.CONTRIB_REPO_SHA }}
+
+      - name: Checkout core repo @ SHA - ${{ env.CORE_REPO_SHA }}
+        uses: actions/checkout@v4
+        with:
+          repository: open-telemetry/opentelemetry-python
+          ref: ${{ env.CORE_REPO_SHA }}
+          path: opentelemetry-python
+
+      - name: Set up Python 3.10
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.10"
+          architecture: "x64"
+
+      - name: Install tox
+        run: pip install tox-uv
+
+      - name: Run tests
+        run: tox -e py310-test-instrumentation-httpx-3-wrapt1 -- -ra
+
+  py310-test-instrumentation-httpx-3-wrapt2:
+    name: instrumentation-httpx-3-wrapt2 
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    steps:
+      - name: Checkout contrib repo @ SHA - ${{ env.CONTRIB_REPO_SHA }}
+        uses: actions/checkout@v4
+        with:
+          repository: open-telemetry/opentelemetry-python-contrib
+          ref: ${{ env.CONTRIB_REPO_SHA }}
+
+      - name: Checkout core repo @ SHA - ${{ env.CORE_REPO_SHA }}
+        uses: actions/checkout@v4
+        with:
+          repository: open-telemetry/opentelemetry-python
+          ref: ${{ env.CORE_REPO_SHA }}
+          path: opentelemetry-python
+
+      - name: Set up Python 3.10
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.10"
+          architecture: "x64"
+
+      - name: Install tox
+        run: pip install tox-uv
+
+      - name: Run tests
+        run: tox -e py310-test-instrumentation-httpx-3-wrapt2 -- -ra
+
   py310-test-util-http:
     name: util-http 
     runs-on: ubuntu-latest