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/scripts/installers/homebrew.sh

@@ -0,0 +1,36 @@
+#!/bin/bash
+################################################################################
+##  File:  homebrew.sh
+##  Desc:  Installs the Homebrew on Linux
+################################################################################
+
+# Source the helpers
+source $HELPER_SCRIPTS/document.sh
+source $HELPER_SCRIPTS/etc-environment.sh
+
+# Install the Homebrew on Linux
+/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"
+eval $(/home/linuxbrew/.linuxbrew/bin/brew shellenv)
+
+# Make brew files and directories writable by any user
+sudo chmod -R o+w $HOMEBREW_PREFIX
+
+# Update /etc/environemnt
+## Put HOMEBREW_* variables
+brew shellenv|grep 'export HOMEBREW'|sed -E 's/^export (.*);$/\1/' | sudo tee -a /etc/environment
+# add brew executables locations to PATH
+brew_path=$(brew shellenv|grep  '^export PATH' |sed -E 's/^export PATH="([^$]+)\$.*/\1/')
+addEtcEnvironmentPathElement "$brew_path"
+
+# Validate the installation ad hoc
+echo "Validate the installation reloading /etc/environment"
+reloadEtcEnvironment
+
+if ! command -v brew; then
+    echo "brew was not installed"
+    exit 1
+fi
+
+# Document the installed version
+echo "Document the installed version"
+DocumentInstalledItem "Homebrew on Linux ($(brew -v 2>&1))"