Load .env from Compose file's directory and cwd

This commit loads dotenv `.env` (exactly that name) from the following location (the later takes
precedence):

- The `.env` file in the Compose file's directory.
- The `.env` file in the current working directory (invoking podman-compose).

This preserves the behavior prior to 1.1.0 and to match with Docker Compose CLI.

Fix: https://github.com/containers/podman-compose/issues/937
Signed-off-by: Genzer <732937+Genzer@users.noreply.github.com>

tests/env-file-tests/README.md

@@ -25,3 +25,13 @@ based on environment variable precedent this command should give podman-rocks-32
 ```
 ZZVAR1=podman-rocks-321 podman-compose -f $(pwd)/project/container-compose.yaml --env-file $(pwd)/env-files/project-1.env up
 ```
+
+_The below test should print three environment variables_
+
+```
+podman-compose -f $(pwd)/project/container-compose.load-.env-in-project.yaml run --rm app
+
+ZZVAR1=This value is overwritten by env-file-tests/.env
+ZZVAR2=This value is loaded from .env in project/ directory
+ZZVAR3=This value is loaded from env-file-tests/.env
+```

tests/env-file-tests/project/container-compose.load-.env-in-project.yaml

@@ -0,0 +1,11 @@
+services:
+  app:
+    image: busybox
+    command: ["/bin/busybox", "sh", "-c", "env | grep ZZ"]
+    tmpfs:
+      - /run
+      - /tmp
+    environment:
+      ZZVAR1: $ZZVAR1
+      ZZVAR2: $ZZVAR2
+      ZZVAR3: $ZZVAR3