Support AT command with no success result code

[chinglee-iot]

This PR adds no success result code command to support the issue #128.

Some cellular modem has command that doesn't reply success result code like "OK" to indicate status.
In the example, SIM8000C has AT+CIFSR command that only returns IP address.

AT+CIFSR
100.83.218.17   // Only IP address is returned in the response. No success result code.

Error result code is still returned by the modem.

AT+CIFSR
ERROR // Error result code is returned by modem

This PR add two new AT command types CELLULAR_AT_WO_PREFIX_NO_RESULT_CODE and CELLULAR_AT_WITH_PREFIX_NO_RESULT_CODE to support this kind of cellular modem. If response is received, this command is regarded as success the response callback will be called. No success result code is required.

Description

• Add CELLULAR_AT_WO_PREFIX_NO_RESULT_CODE AT command type.
• Add CELLULAR_AT_WITH_PREFIX_NO_RESULT_CODE AT command type.

Test Steps

Checklist:

• I have tested my changes. No regression in existing tests.
• I have modified and/or added unit-tests to cover the code changes in this Pull Request.

Related Issue

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