ATD command is used to switch generic device to the data mode
by dialing GPRS_SRC. The generic version of the command was incorrect
`ATD*99##` (containing extra trailing # char, which is accepted by most
devices). Command has been fixed, but the extra #'s been kept for devices
that we cannot test (to be fixed in IDFGH-9470).
Closes https://github.com/espressif/esp-protocols/issues/433
at_raw() sends raw string and supports custom pass/fail phrases for the
API to return OK/FAIL. It also returns raw, unprocessed string as
output.
This allows sending custom requests, such as:
* dce->at_raw("", resp, "RDY", "...", 20000) -- waiting for reset
* esp_modem_at_raw(dce, "+++", resp, "DISCONNECTED", "ERROR", 5000) --
exits PPP mode
Closes https://github.com/espressif/esp-protocols/issues/471
Partially addresses https://github.com/espressif/esp-protocols/issues/468
Variable `pos` was meant to hold position of first `,` (comma)
appearance in the parsed string, but due to wrong parantheses it
contained the boolean representation of not equal to `string::npos`
