Add "rtos-api" to bare metal

[evedon]

Summary of changes

Added the bare metal form of the RTOS API since it doesn't add any overhead (except for a little extra compilation time) and has the benefit of minimising differences between RTOS and bare metal modes.

Impact of changes

RTOS APIs are available in bare metal mode.

Migration actions required

None

Documentation

Bare metal documentation needs to be updated. Work in progress for Mbed 6.

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Pull request type

[] Patch update (Bug fix / Target update / Docs update / Test update / Refactor)
[] Feature update (New feature / Functionality change / New API)
[X] 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

@bulislaw @kjbracey-arm

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[ciarmcom]

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

[mbed-ci]

Test run: FAILED

Summary: 1 of 7 test jobs failed
Build number : 1
Build artifacts

Failed test jobs:

• jenkins-ci/mbed-os-ci_dynamic-memory-usage

[0xc0170]

test dynamic failure is known, will be fixed

[0xc0170]

dynamic test restarted

[0xc0170]

Needs more reviews

[evedon]

@bulislaw should approve

[0xc0170]

Bare metal documentation needs to be updated. Work in progress for Mbed 6.

Is there already PR to be added here or will come soon?

[0xc0170]

[X] Major update (Breaking change E.g. Return code change / API behaviour change)

Isn't this minor update - adding new functionality?