cdr: allow disabling CDR by default on new channels

Adds a new option, defaultenabled, to the CDR core to
control whether or not CDR is enabled on a newly created
channel. This allows CDR to be disabled by default on
new channels and require the user to explicitly enable
CDR if desired. Existing behavior remains unchanged.

ASTERISK-29808 #close

Change-Id: Ibb78c11974bda229bbb7004b64761980e0b2c6d1

include/asterisk/cdr.h

@@ -224,6 +224,7 @@ enum ast_cdr_settings {
 	CDR_END_BEFORE_H_EXTEN = 1 << 4,    /*!< End the CDR before the 'h' extension runs */
 	CDR_INITIATED_SECONDS = 1 << 5,     /*!< Include microseconds into the billing time */
 	CDR_DEBUG = 1 << 6,                 /*!< Enables extra debug statements */
+	CDR_CHANNEL_DEFAULT_ENABLED = 1 << 7, /*!< Whether CDR is enabled for each channel by default */
 };
 
 /*! \brief CDR Batch Mode settings */