Build doc on GHA (#3043)

Summary:
The first step to migrate doc build to GHA.

Pull Request resolved: https://github.com/pytorch/audio/pull/3043

Reviewed By: xiaohui-zhang

Differential Revision: D43110816

Pulled By: mthrok

fbshipit-source-id: 91de5f3ac567188e7030f14c2827a202a1901f1a

.github/workflows/build_docs.yml

+name: Build documentation
+
+on:
+  pull_request:
+  push:
+    branches:
+      - nightly
+      - main
+      - release/*
+  workflow_dispatch:
+
+jobs:
+  upload:
+    runs-on: ubuntu-latest
+    needs: build
+    steps:
+    - uses: actions/download-artifact@v3
+      with:
+        name: docs
+    - name: Tweak the doc artifact
+      run: |
+        ls .
+
+    
+  build:
+    strategy:
+      matrix:
+        python_version: ["3.10"]
+        cuda_arch_version: ["11.7"]
+      fail-fast: false
+    uses: pytorch/test-infra/.github/workflows/linux_job.yml@main
+    with:
+      job-name: Build doc
+      runner: linux.g5.4xlarge.nvidia.gpu
+      repository: pytorch/audio
+      gpu-arch-type: cuda
+      gpu-arch-version: ${{ matrix.cuda_arch_version }}
+      timeout: 120
+      upload-artifact: docs
+
+      script: |
+        # Mark Build Directory Safe
+        git config --global --add safe.directory /__w/audio/audio
+
+        # Set up Environment Variables
+        export PYTHON_VERSION="${{ matrix.python_version }}"
+        export CU_VERSION="${{ matrix.cuda_arch_version }}"
+        export CUDATOOLKIT="pytorch-cuda=${CU_VERSION}"
+
+        # Set CHANNEL
+        if [[(${GITHUB_EVENT_NAME} = 'pull_request' && (${GITHUB_BASE_REF} = 'release'*)) || (${GITHUB_REF} = 'refs/heads/release'*) ]]; then
+          export CHANNEL=test
+        else
+          export CHANNEL=nightly
+        fi
+
+        # Create Conda Env
+        conda create --quiet -y --prefix ci_env python="${PYTHON_VERSION}"
+        conda activate ./ci_env
+
+        # Install PyTorch
+        set -ex
+        set +u  # don't know why
+        conda install \
+          --yes \
+          --quiet \
+          -c "pytorch-${CHANNEL}" \
+          -c nvidia "pytorch-${CHANNEL}"::pytorch[build="*${CU_VERSION}*"] \
+          "${CUDATOOLKIT}"
+
+        # Install torchaudio
+        # TODO: Enable NVDec/NVEnc
+        conda install --quiet -y 'ffmpeg>=4.1' pkg-config
+        pip --quiet install cmake>=3.18.0 ninja
+        USE_FFMPEG=1 pip install --progress-bar off -v -e . --no-use-pep517
+
+        # Install build tools
+        conda install --quiet -y -c conda-forge pandoc doxygen pysoundfile
+        pip install --quiet -r docs/requirements.txt -r docs/requirements-tutorials.txt
+
+        # Build docs
+        export BUILD_GALLERY=true
+        (cd docs && make html)
+
+        mv docs/build/html /artifacts/