WIP MIL-007: fetch the framework's qc, follow links, default configuration files

- git submodule update --init --recursive after adding or reusing the framework
- Follow links to the script so SCRIPT_DIR and the checkout are the real ones
- config.env and .env: --config/--env, else ./ in the working folder, else the checkout's
- Name the files used; a file from the working folder needs a yes before any request
- MIL-007 accepted; test fixtures for the qc checklists; tests/test-launch.sh

Work in progress: the README section is not written yet, and four tests of
test-launch.sh fail and two shellcheck warnings remain; they are fixed next.

Task: MIL-007#1
Task: MIL-007#2
Refs #47
Refs #48
Refs #51

src/lib/constants.sh

@@ -37,8 +37,14 @@ readonly CONFIG_KEYS=(GITHUB_API_URL GITHUB_WEB_URL GITEA_URL GITEA_API_URL
   GITHUB_OWNER PROJECT_DIRECTORY ENABLE_PLAN_GATE PROJECT_LICENSE)
 readonly CREDENTIAL_KEYS=(GITHUB_PAT GITHUB_USER GITEA_TOKEN)
 
-CONFIG_FILE="$PROJECT_ROOT/config.env"
-ENV_FILE="$PROJECT_ROOT/.env"
+# The configuration files: named by --config and --env, or chosen by
+# locate_config_file. The origin is named, folder or checkout.
+CONFIG_FILE=""
+ENV_FILE=""
+CONFIG_ORIGIN=""
+ENV_ORIGIN=""
+# The folder the Maintainer started the script in.
+WORKING_FOLDER=""
 TMP_DIR=""
 HAS_JQ=0
 HTTP_STATUS=0