Move mbed tls lib to separate folder

[daniel-cesarini-tridonic-com]

Description

Move mbedtls feature into separate TARGET_MBEDOS_MBEDTLS in order to exclude it from compilation and clean up the codebase. Also solves some compilation issues for combinations of using / not using proper RNG devices.

As a consequence each device that would use MBEDTLS would need to explicitly enable it in targets.json or in mbed_app.json or in some other way.

This PR is related to ARMmbed/mbed-client#526 .

Pull request type

[ ] Fix
[X] Refactor
[ ] New target
[ ] Feature
[ ] Breaking change

---

FYI: @MarceloSalazar @karsev

Internal reference tridonic: @markus-becker-tridonic-com

[0xc0170]

As a consequence each device that would use MBEDTLS would need to explicitly enable it in targets.json or in mbed_app.json or in some other way.

Move mbedtls feature into separate TARGET_MBEDOS_MBEDTLS in order to exclude it from compilation

I do not think this is correct. It was deliberately put into that folder to be available as the rest of the modules in mbed OS.

good example is one opened Pr related #6577

I do not fully understand the compilation issues. But would like to hear more about cleaning up the codebase.

[daniel-cesarini-tridonic-com]

@0xc0170 thank you for the feedback. I will try to improve the solution we are using currently.
Some issues we faced seem to be related to forward porting our application to newer mbed-os versions.

[daniel-cesarini-tridonic-com]

So in general the approach in mbed is to try to have features available in non "TARGET_" or "FEATURES_" folders if they might apply for multiple targets?
What is the rationale behind it?

Thank you.

[sg-]

Also solves some compilation issues for combinations of using / not using proper RNG devices.

Can you give an example of this. Removing mbed-tls from the default compilation doesn't seem the right way to fix this. In general, the mbed-os is building all software capabilities for a single target by default and we're not looking to conditionally compile OS capabilities at the moment.

[ciarmcom]

ARM Internal Ref: IOTSSL-2241

[0xc0170]

We are closing this. Feel free to comment , we would like to understand what issues you were having. we can create a separate issue.