KVStore & derived classes: design docs, implementation & configuration ...

Implement the following:
KVStore base class
TDBStore class
FileSystemStore class
SecureStore class
Global APIs
Configuration framework
Design documentation

reformat to following codeing style rules

update wait_ms() to sleep_for()

Update code according to the reviews ...

* move emac driver to COMPONENT folder
* use mbed rtos C++ API instead of CMSIS API

update targets.json enable EMAC driver for FVP_MPS2 platforms

override default mem-size in lwIP stack config

add FVP EMAC driver

add lan91c111 drivers for FVP MPS2 platfrom

Merge pull request #8763 from cmonr/rollup-b.1 ...

Rollup PR: Retest CI-troubled PRs target for 5.11 v2

Merge branch 'david_unity_error_code' of ssh://github.com/davidsaada/mbed-os into rollup-b.1

Merge branch 'prepare_for_mbedos511' of ssh://github.com/artokin/mbed-os into rollup-b.1

Merge branch 'david_buffered_bd_perf' of ssh://github.com/davidsaada/mbed-os into rollup-b.1

Merge branch 'fix_astyle_error' of ssh://github.com/0xc0170/mbed-os into rollup-b.1

Merge branch 'Lora_compliance' of ssh://github.com/AnttiKauppila/mbed-os into rollup-b.1

Merge pull request #8685 from bridadan/clean_up_deprecated_feature_code ...

Clean up deprecated feature code

Merge pull request #8753 from 0xc0170/dev_rollup ...

Rollup PR: Retest bundled PRs that experienced CI issues

Merge branch 'lora_ut_fix' of https://github.com/AnttiKauppila/mbed-os into dev_rollup

Merge branch 'master' of https://github.com/ConradBraam/mbed-os into dev_rollup

Merge branch 'ONME-3852' of https://github.com/mtomczykmobica/mbed-os into dev_rollup

Merge branch 'wio3g' of https://github.com/SeeedJP/mbed-os into dev_rollup

Merge branch 'Musca_march' of https://github.com/deepikabhavnani/mbed-os into dev_rollup

Merge branch 'platform-lib-whitespace-patch' of https://github.com/kegilbert/mbed-os into dev_rollup

Merge branch 'remove-filer-paths' of https://github.com/theotherjimmy/mbed into dev_rollup

Merge branch 'feature-emac-mxrt1050' of https://github.com/NXPmicro/mbed into dev_rollup

Merge branch 'master' of https://github.com/kyliuxing/mbed-os into dev_rollup

unittest: fix stubs coding style

cellular: fix test coding style

cellular: fix onboard cellular coding style

Add a Unity macro to assert on platform error code difference

Improve the efficiency of BufferedBlockDevice