Extend tests for memap

[MarceloSalazar]

Description

• Type: Enhancement
• Priority: Major

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Enhancement

Need to extend tests for memap to catch potential regression problems when parsing multiple memory map files for multiple toolchains.

Depends on: #4392

[theotherjimmy]

Thanks for putting up this issue so that we can track it!

[ciarmcom]

ARM Internal Ref: MBOTRIAGE-804

[MarceloSalazar]

Tests are available here: https://github.com/ARMmbed/mbed-os/tree/master/tools/test/memap