Support acloud list command.

Enable the ability to list remote instances created by the user
and disply the info of instances including avd spec and status.

Bug: 118405737
Test: acloud list && acloud list -v && acloud delete
atest acloud_test

Change-Id: I8420f69c8f8c30046eeffe95c5b5d2d184ec4738
diff --git a/internal/constants.py b/internal/constants.py
index 0ef4156..2825b45 100755
--- a/internal/constants.py
+++ b/internal/constants.py
@@ -105,8 +105,6 @@
 ADB_BIN = "adb"
 
 LABEL_CREATE_BY = "created_by"
-LABEL_FLAVOR = "flavor"
-LABEL_TYPE = "avd_type"
 
 # for list and delete cmd
 INS_KEY_NAME = "name"
@@ -117,8 +115,8 @@
 INS_KEY_ADB = "adb"
 INS_KEY_VNC = "vnc"
 INS_KEY_CREATETIME = "creationTimestamp"
-INS_KEY_AVD_TYPE = LABEL_TYPE
-INS_KEY_AVD_FLAVOR = LABEL_FLAVOR
+INS_KEY_AVD_TYPE = "avd_type"
+INS_KEY_AVD_FLAVOR = "flavor"
 INS_KEY_IS_LOCAL = "remote"
 INS_STATUS_RUNNING = "RUNNING"
 LOCAL_INS_NAME = "local-instance"