ESP8266: Convert to Chrono

[kjbracey]

Summary of changes

Convert ESP8266 driver wrapper to use new APIs from #12425.

Impact of changes

Eliminate use of deprecated APIs

Migration actions required

n/a

Documentation

None

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Pull request type

[] Patch update (Bug fix / Target update / Docs update / Test update / Refactor)
[X] 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

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Reviewers

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[ciarmcom]

@kjbracey-arm, thank you for your changes.
@ARMmbed/mbed-os-ipcore @ARMmbed/mbed-os-maintainers please review.

[adbridge]

@kjbracey-arm what is the state of this now ?

[kjbracey]

Waiting for #12425, like all the other Chrono PRs. Added the missing label.

[0xc0170]

I restarted travis, however it failed (not certain due to rebase or there is an error in this PR) , so if again, please review

[kjbracey]

CI started

[mbed-ci]

Test run: SUCCESS

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