Fix build of CYTFM_064B0S2_4343W

[multiplemonomials]

Summary of changes

This PR fixes a couple issues preventing the build of the CYTFM_064B0S2_4343W target:

• Missing dependency on cysecuretools in requirements.txt prevented the post build script from running
• The post build script was trying to create and sign tfm_s.hex in the build dir for every target that compiled, so if multiple targets built in parallel, the build would fail with a corrupt file error.
• Missing dependency on mbed-psa for the MCU target, added this the same as for the Nuvoton target

Impact of changes

Migration actions required

Documentation

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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

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

Verified that this target now compiles with these fixes

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[ccli8]

The post build script was trying to create and sign tfm_s.hex in the build dir for every target that compiled, so if multiple targets built in parallel, the build would fail with a corrupt file error.

Curious about it. Do parallel builds share the same build dir? Then separate build dir will be more meaningful.

[multiplemonomials]

Well, if you compile with e.g. ninja -j4 or make -j4, that could result in up to 4 instances of the post build script running at the same time. If the post build script is trying to manipulate a fixed file path in the build directory, that will cause problems.

[multiplemonomials]

@ccli8 @JohnK1987 good to approve?