Fix all Doxygen errors and make any future errors fatal (#118) ...

* Start working on fixing doxygen warnings

* Upgrade doxyfile to Doxygen 1.9.1

* Clean up some unmatched groups and add some exclusions

* Fix docs for rtos::ThisThread not showing up

* Fix up KV store docs

* Fix incorrect @files, some more incorrect groups

* Fix lots of broken links

* Start fixing mbedtls groups

* Fix more mbedtls docs

* Fix remaining mbedtls files with missing or incorrect grouping

* Fix a huge amount of PSA docs errors

* Fix a few more mbedtls docs errors

* Fix __cplusplus not defined for docs, clean up call in callback typedef, fix some docs errors

* Fix some broken doc links in HAL headers

* Fix more PSA doc errors

* Fix some doxygen errors in networking code

* Fix lots of network related doc errors

* Try and fix some CI failures

* Use Doxygen Action instead of doxygen in Mbed container to get the right version

* Try removing docs check

* Add first part of doxygen action

* Add next part of doxygen action

* Fix yaml syntax error

* Add in license check fix

* Try using verbose scancode

* Fix some more docs issues, workaround scancode-toolkit#3179

* Clean up the LoRaRadio get_state() function on each implementation.  Also fix some other compile and doc errors.

* Fix all remaining doxygen errors

* Fix escaping, for realsies this time

* Remove Doxygen unsupported config options, fix some more get_status() declarations

* Fix some UNITTESTS build errors

* Fix one more compile error

* Another unittest error

Create a kvstore_global_api for the global API and KVMap

Turn TDBStore and FileSystemStore into standalone libraries

TDBStore: the work buffer is at least the program size or 64 bytes ...

Previously, we always set the work buffer to 64 bytes, without
checking it was no less the actual program size. But we can't
simply switch to use the program size for the work buffer,
because if it's too small (e.g. 1 byte in some cases), we
will not be able to read the status header (24 bytes), and
small buffers means more underlying write operations and
lower efficiency.

This PR changes the work buffer size to be the program size,
or 64 bytes as an absolute minimum like before.

Refactore storage/kvstore directory