add Homebrew on Linux (#589)

* Add homebrew installation and validation scripts

* Update `/etc/environment` in `updatepath.sh` script

Keep this code for sake of compatibility with the existing installation logic. It will be changed in its own PR

* Remove env. variables from homebrew validation task

* Move reboot to the dedicated script and task

Co-authored-by: Sergey Dolin <v-sedoli@micorosoft.com>

images/linux/ubuntu1804.json

@@ -135,6 +135,36 @@
             ],
             "execute_command": "sudo sh -c '{{ .Vars }} {{ .Path }}'"
         },
+        {
+            "type": "shell",
+            "scripts": [
+                "{{template_dir}}/scripts/installers/homebrew.sh"
+            ],
+            "environment_vars": [
+                "METADATA_FILE={{user `metadata_file`}}",
+                "HELPER_SCRIPTS={{user `helper_script_folder`}}",
+                "DEBIAN_FRONTEND=noninteractive"
+            ],
+            "execute_command": "/bin/sh -c '{{ .Vars }} {{ .Path }}'"
+        },
+        {
+            "type": "shell",
+            "expect_disconnect": true,
+            "scripts": [
+                "{{template_dir}}/scripts/base/reboot.sh"
+            ],
+            "execute_command": "/bin/sh -c '{{ .Vars }} {{ .Path }}'"
+        },
+        {
+            "type": "shell",
+            "pause_before": "30s",
+            "timeout": "10m",
+            "start_retry_timeout": "10s",
+            "scripts": [
+                "{{template_dir}}/scripts/installers/homebrew-validate.sh"
+            ],
+            "execute_command": "/bin/sh -c '{{ .Vars }} {{ .Path }}'"
+        },
         {
             "type": "shell",
             "scripts": [