Add ability to copy files to a container before it is started (#180)

Author: dmitri-gb

README.md

@@ -178,6 +178,18 @@ const container = await new GenericContainer("postgres")
   .start();
 ```
 
+Copy a file to a container before it is started:
+
+```javascript
+const { GenericContainer } = require("testcontainers");
+
+const container = await new GenericContainer("postgres")
+  .withExposedPorts(5432)
+  .withCopyFileToContainer("/local/file.txt", "/remote/file1.txt")
+  .withCopyContentToContainer("hello world", "/remote/file2.txt")
+  .start();
+```
+
 Creating a container with environment variables:
 
 ```javascript

package-lock.json

@@ -32,6 +32,7 @@
   },
   "dependencies": {
     "@types/dockerode": "^3.2.1",
+    "archiver": "^5.2.0",
     "byline": "^5.0.0",
     "debug": "^4.3.1",
     "docker-compose": "^0.23.5",
@@ -45,6 +46,7 @@
   },
   "devDependencies": {
     "@elastic/elasticsearch": "^7.10.0",
+    "@types/archiver": "^5.1.0",
     "@types/byline": "^4.2.32",
     "@types/debug": "4.1.5",
     "@types/glob": "^7.1.3",