Smoke Test: Add R dependencies (#3860)

### Intent

Addresses #3844 

Switches workflow to use a single source of truth for R dependencies
from the qa-example-content repo.

### Approach

Updated Github action to install R dependencies from DESCRIPTION file.

Updated README with new instructions.

### QA Notes

Smoke tests pass using new method.

.github/workflows/positron-full-test.yml

@@ -31,7 +31,8 @@ jobs:
         run: |
           curl -Ls https://github.com/r-lib/rig/releases/download/latest/rig-linux-"$(arch)"-latest.tar.gz | $(which sudo) tar xz -C /usr/local
           rig add 4.4.0
-          Rscript -e "install.packages(c('arrow', 'connections', 'RSQLite', 'readxl', 'lubridate'))"
+          curl https://raw.githubusercontent.com/posit-dev/qa-example-content/main/DESCRIPTION --output DESCRIPTION
+          Rscript -e "pak::local_install_dev_deps(ask = FALSE)"
 
       - uses: actions/setup-node@v3
         with:
@@ -119,6 +120,7 @@ jobs:
 
       - name: Set TestRail Run Title
         id: set-testrail-run-title
+        if: always()
         run: echo "TESTRAIL_TITLE=$(date +'%Y-%m-%d') Smoke Tests" >> $GITHUB_ENV
 
       - name: Upload Test Results to TestRail

test/smoke/README.md

@@ -138,7 +138,8 @@ python -m pip install matplotlib ipykernel
 The current commands for R packages:
 
 ```
-Rscript -e "install.packages(c('arrow', 'connections', 'RSQLite', 'readxl', 'lubridate'))"
+curl https://raw.githubusercontent.com/posit-dev/qa-example-content/main/DESCRIPTION --output DESCRIPTION
+Rscript -e "pak::local_install_dev_deps(ask = FALSE)"
 ```
 
 ## Build step
@@ -158,6 +159,8 @@ Before any of the tests start executing the test framework clones down the [QA C
 
 For Python, add any package requirements to the `requirements.txt` file in the root of the [QA Content Examples](https://github.com/posit-dev/qa-example-content) repo.  We generally do NOT pin them to a specific version, as test can be run against different versions of python and conflicts could arise.  If this becomes a problem, we can revisit this mechanism.
 
+For R, add any package requirements to the "imports" section of the `DESCRIPTION` file in the root of the [QA Content Examples](https://github.com/posit-dev/qa-example-content) repo.
+
 ## Running tests
 
 Once you have the build watcher running you can run the smoke tests with the debug action `Launch Smoke Test`. (It's near the bottom of the debug dropdown.)