Fixes ncp-client not waiting for modem ready on cold boot

[technobly]

Problem

• After the UART fixes of [gen3] hal: fixes the issue that UARTE RX may loss data. #2698, the UART is a bit faster now and that has surfaced some lurking issues. The Quectel NCP Client was not waiting for the modem to be ready on cold boot, causing a boot loop from CFUN=1,0 failing in initReady()

Solution

• Add a retry scheme for CFUN=1,0 on initReady() only at this time.

Steps to Test

• Cold boot the device and ensure any CFUN errors are handled, retried and the device boots successfully.
• All integration tests should pass, especially the cold boot SLO test.

References

#2698

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Completeness

• User is totes amazing for contributing!
• Contributor has signed CLA (Info here)
• Problem and Solution clearly stated
• Run unit/integration/application tests on device
• Added documentation
• Added to CHANGELOG.md after merging (add links to docs and issues)