tests: logging: copy dictionary logging sample into tests

This is in preparation for introducing pytest to test the output
of dictionary logging. Code is the same, but the testcase.yaml
is trimmed to only those that can be tested.

Note that a copy is made instead of moving the whole sample over
is simply due to various documentation having references to
the sample. Since RST files under tests/ are not parsed for
zephyr:code-sample:<name>, the linking would have been vanished.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>