feat(avd): add avd plugin

plugins/avd/README.md

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+# avd plugin
+
+The avd plugin provides aliases for Android Virtual Device / Android
+Emulator commands.
+
+To use it, add avd to the plugins array of your zshrc file:
+
+```zsh
+plugins=(... avd)
+```
+
+## Requirements
+
+In order to make this work, you will need to have the Android `emulator`
+tool set up in your path. This plugin will try to find that tool in
+`$ANDROID_HOME` as a last resort, however it will make it slower and may
+not work as expected.
+
+## Functions
+
+- `avds` - Lists all the AVDs
+- `avd [-v] <n>` - Launches n-th AVD from the AVDs list printed by
+  `avds`
+  - `-v` will let stdout and stderr print to the console which is
+    disabled by default to avoid the clutter
+- `find_emulator` - Tries to find the `emulator` tool either in your
+  path or `$ANDROID_HOME` directory
+
+## Aliases
+
+- `emus` - Same as `avds`
+- `emu [-v] <n>` - Same as `avd [-v] <n>`
+
+## Exemplary usage:
+```
+~/
+> avds
+Pixel_2_API_30
+Samsung_Tab_A_2019_API_25
+Samsung_Tab_A_2019_API_29
+
+~/
+> avd 2
+Starting emulator: Samsung_Tab_A_2019_API_25
+[3] 33463
+```

plugins/avd/avd.plugin.zsh

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+function find_emulator() {
+  local emulator_found
+
+  if [[ -n $(command -v emulator) ]]; then
+    emulator_found="emulator"
+  elif [[ -d "$ANDROID_HOME" ]]; then
+    # If there is no emulator in the path, try to find it in $ANDROID_HOME if it
+    # is defined.
+    emulator_found=$(find "$ANDROID_HOME" -name emulator -type f | head -1)
+  fi
+
+  if [[ -n $emulator_found ]]; then
+    echo "$emulator_found"
+  else
+    cat <<< "Emulator not found" 1>&2
+
+    # Use "emulator" even if it's not found just to let the other functions fail
+    # later.
+    echo "emulator"
+  fi
+}
+
+function avds() {
+  local emulator_path
+  emulator_path=$(find_emulator)
+  eval "$emulator_path -list-avds"
+}
+
+function avd() {
+  help() {
+    echo "Usage: avd [-v] [AVD position on the list]"
+    avds
+  }
+
+  local OPTIND o verbose avd_number avd_name avds_count emulator_path
+  while getopts ":v" o; do
+    case "$o" in
+      v)
+        verbose=1;;
+      *)
+        help; return;;
+    esac
+  done
+
+  shift $((OPTIND-1))
+
+  avd_number="$1"
+
+  if [[ -z $avd_number ]]; then
+    help
+    return
+  fi
+
+  avds_count=$(avds | wc -l | grep -Eo '[0-9]+') || return
+
+  if [[ $avds_count -le 0 ]]; then
+    echo "No AVDs found"
+    return
+  fi
+
+  if [[ ($avd_number -lt 1 || $avd_number -gt $avds_count) ]]; then
+    echo "The number must be in 1..${avds_count}"
+    return
+  fi
+
+  avd_name=$(avds | head -"$avd_number" | tail -1)
+  echo "Starting emulator: $avd_name"
+
+  emulator_path=$(find_emulator)
+  cmd_to_execute="$emulator_path -avd $avd_name"
+
+  if [[ $verbose -eq 1 ]]; then
+    eval "$cmd_to_execute"
+  else
+    eval "$cmd_to_execute" > /dev/null 2>&1
+  fi
+}
+
+alias emus="avds"
+alias emu="avd"
+