Split integration tests for filesystem and network

[MarceloSalazar]

Description

This PR splits integration tests to let developers run individual tests for filesystem, network or stress (fs+net) depending on what the platform supports.

This is an example of platforms and tests that can be run:

	fs-single	net-single	stress (fs+net)
K64F (sd+eth)	✔️	✔️	✔️
NUCLEO_F429ZI (eth)	❌	✔️	❌
DISCO_L496AG (qspi)	✔️	❌	❌

The way to run the integration tests has not changed, but no valid test cases are now skipped.
mbed test -t <toolchain> -m <target> -DINTEGRATION_TESTS

Pull request type

[ ] Fix
[ ] Refactor
[ ] Target update
[ ] Functionality change
[ ] Docs update
[X] Test update
[ ] Breaking change

Reviewers

@jamesbeyond

FYI @maclobdell @toyowata

[ciarmcom]

@MarceloSalazar, thank you for your changes.
@jamesbeyond @toyowata @maclobdell @ARMmbed/mbed-os-maintainers please review.

[0xc0170]

Add also details in the commit message.

I would suggest moving tests one commit, removal of flashiap another one - two separate things.

[MarceloSalazar]

Discussed with @jamesbeyond and agreed to re-enable flashiap.

@0xc0170 this is ready for review - hopefully on time for code freeze ;-)

[0xc0170]

CI started meanwhile

[mbed-ci]

Test run: FAILED

Summary: 2 of 4 test jobs failed
Build number : 1
Build artifacts

Failed test jobs:

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

[0xc0170]

CI restarted

[mbed-ci]

Test run: SUCCESS

Summary: 5 of 5 test jobs passed
Build number : 2
Build artifacts

[0xc0170]

Travis failed to report , nothing at all. reopen in a second to get a new update

[0xc0170]

I can't find it even on Travis (11703 PR not in the list there , I browsed back to 11700-2 PRs), something went wrong. @MarceloSalazar can you create new PR, that should go quickly in? based on all here.

[0xc0170]

I'll try to close/reopen one more time otherwise we need a new PR :/