NANO130: Support dynamic heap configuration on IAR

[ccli8]

Summary of changes

This PR is continuation of #12047 and tries to fix static SRAM OOM further by supporting dynamic heap configuration on IAR. In this PR, for IAR toolchain, heap is configured to 1KiB at a minimum and expandable to available SRAM. This requires IAR 8.x.

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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

[x] No Tests required for this change (E.g docs only update)
[] Covered by existing mbed-os tests (Greentea or Unittest)
[] Tests / results supplied as part of this PR

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Reviewers

@mprse @0xc0170

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[ciarmcom]

@ccli8, thank you for your changes.
@mprse @0xc0170 @Ronny-Liu @ARMmbed/mbed-os-maintainers please review.

[mbed-ci]

Test run: FAILED

Summary: 4 of 4 test jobs failed
Build number : 1
Build artifacts

Failed test jobs:

• jenkins-ci/mbed-os-ci_unittests
• jenkins-ci/mbed-os-ci_build-GCC_ARM
• jenkins-ci/mbed-os-ci_build-ARM
• jenkins-ci/mbed-os-ci_build-IAR

[0xc0170]

Will restart the tests (internal fault)

[0xc0170]

CI restarted

[mbed-ci]

Test run: SUCCESS

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