Update cellular drivers/tests for UBLOX_C030_R412M

[AriParkkila]

Summary of changes

Update cellular drivers/tests for UBLOX_C030_R412M:

• Enable IP over PPP on UBLOX_C030_R41XM
• Fix UBLOX_AT UDP/IP driver
• Fix UDPSOCKET_ECHOTEST to handle oversized packets
• Enable SYNCHRONOUS_DNS_CACHE just for NSAPI_PPP_AVAILABLE
• Add UBLOX_C030_R412M target in CellularInterface.json

Impact of changes

Migration actions required

Documentation

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Pull request type

[x] Patch update (Bug fix / Target update / Docs update / Test update / Refactor)
[] Feature update (New feature / Functionality change / New API)
[] Major update (Breaking change E.g. Return code change / API behaviour change)

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Test results

[] No Tests required for this change (E.g docs only update)
[x] Covered by existing mbed-os tests (Greentea or Unittest)
[] Tests / results supplied as part of this PR

Mbed OS greentea tests PASS with mbed test -m UBLOX_C030_R412M --app-config tools/test_configs/CellularInterface.json:

• Test suites -n network-interface / tests-netsocket-*
• On both LWIP and modem IP stack: lwip.ppp-enabled: true/false

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Reviewers

@ARMmbed/team-ublox

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[ciarmcom]

@AriParkkila, thank you for your changes.
@ARMmbed/mbed-os-wan @ARMmbed/mbed-os-tools @ARMmbed/mbed-os-ipcore @ARMmbed/mbed-os-test @ARMmbed/mbed-os-maintainers please review.

Pull request has been modified.

[0xc0170]

CI started

[mbed-ci]

Test run: SUCCESS

Summary: 12 of 12 test jobs passed
Build number : 1
Build artifacts

[0xc0170]

This PR shall be ready, but @ARMmbed/team-ublox was requested for review.

[0xc0170]

@ARMmbed/team-ublox We will move forward. If something found, will be treated separately.