Facilitate testing PRs from an external repo hosted on GH

Closes #129 (closed)

This will enable us to define the upstream and downstream repos along with their respective branches that need to be set as an external repo (i.e. hosted external to gitlab for eg. Github) for this project to function.

.gitlab-ci.yml

@@ -44,9 +44,9 @@ workflow:
   - *get_build_date
   - |
     if [ ! -d $CI_PROJECT_DIR/CRI_XCBC ]; then
-      git clone https://github.com/uabrc/CRI_XCBC.git
       cd CRI_XCBC
-      git remote add upstream https://github.com/jprorama/CRI_XCBC.git
+      git clone ${EXT_PR_TARGET_REPO} ${EXT_REPO_DIR}
+      git remote add upstream ${EXT_PR_SRC_REPO}
       cd ..
     fi
   - cd CRI_XCBC