Backport bionic actions CI to sdf9 (gazebosim#311)

Signed-off-by: Steve Peters <scpeters@openrobotics.org>

.github/workflows/linux-ubuntu-bionic.yml

@@ -0,0 +1,72 @@
+name: Ubuntu Bionic / Linux
+
+on: [push, pull_request]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-18.04
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Install base dependencies
+      run: |
+        sudo apt update;
+        sudo apt -y install wget lsb-release gnupg;
+        sudo sh -c 'echo "deb http://packages.osrfoundation.org/gazebo/ubuntu-stable $(lsb_release -cs) main" > /etc/apt/sources.list.d/gazebo-stable.list';
+        sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys D2486D2DD83DB69272AFE98867170598AF249743;
+        sudo apt-get update;
+        sudo apt -y install cmake build-essential curl g++-8 git mercurial libtinyxml-dev libxml2-utils ruby-dev python-psutil cppcheck;
+        sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-8 800 --slave /usr/bin/g++ g++ /usr/bin/g++-8 --slave /usr/bin/gcov gcov /usr/bin/gcov-8;
+        # workaround for https://github.com/rubygems/rubygems/issues/3068
+        # suggested in https://github.com/rubygems/rubygems/issues/3068#issuecomment-574775885
+        sudo gem update --system 3.0.6;
+    - name: Install lcov
+      run: |
+        git clone https://github.com/linux-test-project/lcov.git -b v1.14;
+        cd lcov;
+        sudo make install;
+        cd ..;
+    - name: Static checking before building - fail fast
+      run: sh tools/code_check.sh
+    - name: Install ignition dependencies
+      run: |
+        sudo apt -y install \
+            libignition-cmake2-dev \
+            libignition-math6-dev \
+            libignition-tools-dev \
+            liburdfdom-dev;
+    - name: cmake
+      run: |
+        mkdir build;
+        cd build;
+        cmake .. -DCMAKE_BUILD_TYPE=coverage;
+    - name: make sdf_descriptions
+      working-directory: build
+      run: make sdf_descriptions
+    - name: make
+      working-directory: build
+      run: make
+    - name: make test
+      env:
+        CTEST_OUTPUT_ON_FAILURE: 1
+      working-directory: build
+      run: make test
+    - name: make coverage
+      working-directory: build
+      run: make coverage VERBOSE=1
+    - name: Upload to codecov
+      working-directory: build
+      # disable gcov output with `-X gcovout -X gcov`
+      run: bash <(curl -s https://codecov.io/bash) -X gcovout -X gcov
+    - name: make install
+      working-directory: build
+      run: sudo make install
+    - name: Compile example code
+      working-directory: examples
+      run: |
+        mkdir build;
+        cd build;
+        cmake ..;
+        make;
+        ./simple ../simple.sdf;