Cellular: updated cellular context flags and cid in ublox-api

[mudassar-ublox]

Description (required)

Updated cellular context flags and cid in ublox_at_cellularcontext for UBLOX_C030_R410M and UBLOX_C030_R412M (CAT-M1 and NB1). In these cases R410M and R412M modem its self activates context, so reading which context is active, updating _cid and flags.

Summary of change (What the change is for and why)

Documentation (Details of any document updates required)

---

Pull request type (required)

[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)

---

Test results (required)

[] 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

---

Reviewers (optional)

---

Release Notes (required for feature/major PRs)

Summary of changes

Impact of changes

Migration actions required

[ciarmcom]

@mudassar-ublox, thank you for your changes.
@ARMmbed/mbed-os-wan @ARMmbed/mbed-os-maintainers please review.

[mbed-ci]

Test run: SUCCESS

Summary: 11 of 11 test jobs passed
Build number : 2
Build artifacts