Add package and linter checks to CI

.Rbuildignore

@@ -1,2 +1,3 @@
 ^\.lintr$
-^LICENSE\.md$
+^LICENSE\.md$
+^\.github$

.github/workflows/r-tests.yml

@@ -36,3 +36,55 @@ jobs:
       - name: Run R tests
         run: |
           Rscript -e 'devtools::test()'
+  
+  check:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
+      - name: Install system dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y libharfbuzz-dev libfribidi-dev libfreetype6-dev pkg-config libcurl4-openssl-dev
+
+      - name: Setup R environment
+        uses: r-lib/actions/setup-r@v2
+        with:
+          r-version: 'latest'
+
+      - name: Install devtools and package dependencies
+        run: |
+          Rscript -e 'install.packages("devtools", dependencies = NA)'
+          Rscript -e 'devtools::install_deps(dep = TRUE)'
+      
+      - name: Check package
+        run: |
+          Rscript -e 'devtools::check()'
+
+  linter:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
+      - name: Install system dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y libharfbuzz-dev libfribidi-dev libfreetype6-dev pkg-config libcurl4-openssl-dev
+
+      - name: Setup R environment
+        uses: r-lib/actions/setup-r@v2
+        with:
+          r-version: 'latest'
+
+      - name: Install devtools and package dependencies
+        run: |
+          Rscript -e 'install.packages("devtools", dependencies = NA)'
+          Rscript -e 'devtools::install_deps(dep = TRUE)'
+      
+      - name: Check linting
+        run: |
+          Rscript -e 'lintr::expect_lint_free()'