Port CI to GitHub Actions

This should emulate the behavior of the previous Azure Pipeline CI build. The only exception is the build artifact is
now stored as a GitHub Actions workflow artifact rather than on Azure Pipeline.

To work around the actions/upload-artifact action's behavior of removing executable file permissions from the workflow
artifacts, I uploaded the archive file as the artifact. The downside to this workaround is you get a .zip file inside of
a .zip file:

binary_Linux.zip
|_ arduino-language-server_Linux_amd64.zip
    |_ arduino-language-server

.github/workflows/build.yml

@@ -0,0 +1,66 @@
+name: build
+
+on:
+  push:
+    branches:
+      - master
+  schedule:
+    - cron: '0 4 * * MON-FRI' # run every weekday at 4AM (https://docs.github.com/en/actions/reference/events-that-trigger-workflows#scheduled-events-schedule)
+  workflow_dispatch:
+  pull_request:
+    branches:
+      - master
+
+jobs:
+
+  build:
+    env:
+      BUILD_OUTPUT_DIRECTORY: dist
+      EXECUTABLE_NAME: arduino-language-server
+    strategy:
+      matrix:
+        config:
+          - os: ubuntu-16.04
+            ExecutableSuffix: ''
+            Exports: ''
+          - os: macos-latest
+            ExecutableSuffix: ''
+            Exports: 'CGO_ENABLED=1 MACOSX_DEPLOYMENT_TARGET=10.14 '
+          - os: windows-2016
+            ExecutableSuffix: '.exe'
+            Exports: ''
+    runs-on: ${{ matrix.config.os }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Install Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: '1.13'
+
+      - name: Build and Test
+        run: |
+          ${{ matrix.config.Exports }}go build -o "${{ github.workspace }}/${{ env.BUILD_OUTPUT_DIRECTORY }}/${{ runner.OS }}_amd64/${{ env.EXECUTABLE_NAME }}${{ matrix.config.ExecutableSuffix }}"
+          go test ./...
+
+      - name: Create archive
+        run: 7z a "${{ github.workspace }}/${{ env.BUILD_OUTPUT_DIRECTORY }}/archive/${{ env.EXECUTABLE_NAME }}_${{ runner.OS }}_amd64.zip" "${{ github.workspace }}/${{ env.BUILD_OUTPUT_DIRECTORY }}/${{ runner.OS }}_amd64/*"
+
+      - name: Upload Workflow Artifact [GitHub Actions]
+        uses: actions/upload-artifact@v2
+        with:
+          name: binary_${{ runner.OS }}
+          # this makes the artifact a .zip of the .zip archive, which is currently necessary to preserve the executable file permissions
+          # see: https://github.com/actions/upload-artifact/issues/38
+          path: ${{ env.BUILD_OUTPUT_DIRECTORY }}/archive/${{ env.EXECUTABLE_NAME }}_${{ runner.OS }}_amd64.zip
+
+      - name: Publish Nightly [S3]
+        if: github.event_name == 'schedule` || github.event_name == 'workflow_dispatch'
+        uses: kittaakos/upload-s3-action@v0.0.1
+        with:
+          aws_key_id: ${{ secrets.AWS_ACCESS_KEY_ID }}
+          aws_secret_access_key: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
+          aws_bucket: arduino-downloads-prod-beagle
+          source_dir: ${{ env.BUILD_OUTPUT_DIRECTORY }}/archive/${{ env.EXECUTABLE_NAME }}_${{ runner.OS }}_amd64.zip
+          destination_dir: arduino-language-server/nightly/