feat: add GetInstallEnvs utility function for configuration management

- Introduced a new function GetInstallEnvs in config.go to retrieve installation environment variables
- Added DefaultInstallEnvs constant with an empty default value
- Implemented fallback mechanism to split DefaultInstallEnvs if no configuration is found
- Enhances configuration flexibility for installation environments

core/utils/config.go

@@ -28,6 +28,7 @@ const (
 	DefaultApiPath             = "/api"
 	DefaultNodeMaxRunners      = 0 // 0 means no limit
 	DefaultInstallRoot         = "/app/install"
+	DefaultInstallEnvs         = ""
 	MetadataConfigDirName      = ".crawlab"
 	MetadataConfigName         = "config.json"
 	DefaultPyenvPath           = "/root/.pyenv"
@@ -250,6 +251,13 @@ func GetInstallRoot() string {
 	return DefaultInstallRoot
 }
 
+func GetInstallEnvs() []string {
+	if res := viper.GetStringSlice("install.envs"); res != nil {
+		return res
+	}
+	return strings.Split(DefaultInstallEnvs, ",")
+}
+
 func GetPyenvPath() string {
 	if res := viper.GetString("install.pyenv.path"); res != "" {
 		return res