TEST: Refactor mbedmicro tests to use utest framework

[jamesbeyond]

Summary of changes

Some mbedmicro tests are in the old format, they are not using the utest framework.
Users report they causing inconsistent behavior with those tests which use utest framework.
So refactor mbedmicro tests to use utest framework.

Impact of changes

Migration actions required

Documentation

Not Required

---

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)

---

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

---

Reviewers

@maclobdell

---

[ciarmcom]

@jamesbeyond, thank you for your changes.
@maclobdell @ARMmbed/mbed-os-maintainers please review.

[0xc0170]

Ci started

[mbed-ci]

Test run: SUCCESS

Summary: 5 of 5 test jobs passed
Build number : 1
Build artifacts