Move drivers from components to connectivity

[LDong-Arm]

Summary of changes

We are gradually migrating connectivity features (e.g. WiFi, cellular, BLE, etc.) to a new directory structure:

connectivity
├── wifi
├── cellular
├── [...]
├── drivers       // target drivers
│   ├── wifi
│   ├── cellular
│   ├── [...]

This PR moves the existing WiFi, cellular and 802.15.4_RF drivers from components/ to the newly proposed connectivity/drivers/ directory.

Not covered: BLE, NFC & drivers outside components/ - to be covered by separate PRs.

Impact of changes

Migration actions required

Documentation

None.

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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)
[x] Tests / results supplied as part of this PR

Manual testing (compilation):

• WiFi: mbed-os-example-wifi for NUCLEO_F429ZI - esp8266-driver
• cellular: mbed-os-example-cellular for DISCO_L496AG - COMPONENT_STMOD_CELLULAR
• 802.15.4_RF: nanostack-border-router for any target - atmel-rf-driver

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Reviewers

@ARMmbed/mbed-os-core @bulislaw @0xc0170

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[ciarmcom]

@LDong-Arm, thank you for your changes.
@0xc0170 @bulislaw @ARMmbed/mbed-os-maintainers please review.

[rajkan01]

LGTM.

[mbed-ci]

Test run: SUCCESS

Summary: 6 of 6 test jobs passed
Build number : 1
Build artifacts

[adbridge]

Re-running ci as this passed 8 days ago

[mbed-ci]

Test run: SUCCESS

Summary: 6 of 6 test jobs passed
Build number : 2
Build artifacts