Support container environment overrides

Author: brice burgess

README.md

@@ -38,9 +38,10 @@ This action is great for executing migrations or other pre/post deployment steps
     override-container-command: |
       /bin/sh
       -c
-      php artisan migrate --force --ansi && \
-      php artisan db:seed --force --ansi && \
-      php artisan config:clear --ansi
+      php artisan migrate --force --ansi && php artisan db:seed --force --ansi
+    override-container-environment: |
+      AWS_REGION=us-east-1
+      FOO=baz
 ```
 
 #### Minimal example

action.yml

@@ -40,6 +40,10 @@ inputs:
     description: >-
       The command to run on the container if `override-container` is passed.
     required: false
+  override-container-environment:
+    description: >-
+      Add or override existing environment variables if `override-container` is passed. Provide one per line in key=value format.
+    required: false
   tail-logs:
     description: >-
       If set to true, will try to extract the logConfiguration for the first container in the task definition. If