Add CI job that cargo-checks all services (#543)

    - name: Cargo Clippy

      run: cargo clippy -- -D warnings

      working-directory: aws-sdk

  all-services-check:

    name: cargo check all services

    runs-on: ubuntu-latest

    steps:

    - uses: actions/checkout@v2

    - uses: actions/cache@v2

      name: Gradle Cache

      with:

        path: |

          ~/.gradle/caches

          ~/.gradle/wrapper

        key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle*') }}

        restore-keys: |

          ${{ runner.os }}-gradle-

    - uses: actions-rs/toolchain@v1

      with:

        toolchain: ${{ env.rust_version }}

        components: ${{ env.rust_toolchain_components }}

        default: true

    - name: Set up JDK

      uses: actions/setup-java@v1

      with:

        java-version: ${{ env.java_version }}

    - name: generate a check all services

      run: ./gradlew :aws:sdk:cargoCheck

      env:

        GENERATE_ALL_SERVICES: 'true'

    - name: Generate a name for the SDK

      id: gen-name

      run: echo "name=${GITHUB_REF##*/}" >> $GITHUB_ENV

    - uses: actions/upload-artifact@v2

      name: Upload SDK Artifact

      with:

        name: aws-sdk-all-services-${{ env.name }}-${{ github.sha }}

        path: |

          aws/sdk/build/aws-sdk/

          !aws/sdk/build/aws-sdk/target

    override fun section(section: OperationSection): Writable {

        return when (section) {

            is OperationSection.MutateRequest -> writable {

                // TODO: this needs to be customized for individual operations, not just `default_config()`

                rustTemplate(

                    """

                ##[allow(unused_mut)]