Add support for post-install-script being a URL

tmt/steps/provision/artemis.py

@@ -548,7 +548,22 @@ def _create(self) -> None:
         # TODO: spot instance
 
         if self.post_install_script:
-            data['post_install_script'] = self.post_install_script
+            if tmt.utils.is_url(self.post_install_script):
+                try:
+                    response = requests.get(self.post_install_script)
+                    response.raise_for_status()
+
+                except requests.exceptions.RequestException:
+                    raise ArtemisProvisionError(
+                        "failed to get the post_install_script file")
+
+                post_install_script = response.text
+            else:
+                self.info('post-install-script argument is treated as a raw script')
+
+                post_install_script = post_install_script.replace('\\n', '\n')
+
+            data['post_install_script'] = post_install_script
 
         if self.log_type:
             data['log_types'] = list({tuple(log.split('/', 1)) for log in self.log_type})