tools: owners: handle matchers
tools: owners: handle matchers

Enhance the owners tool to parse the 'matchers' directives in order
to add additional owners and reviewers.

Tested:

* Created a bogus commit in 'docs' to detect GPIO and MCTP matchers.
* Created a bogus commit in 'smbios-mdr' to detect change to
  speed_select.hpp.

```
$ tools/owners --path ../docs reviewers && echo "..." && tools/owners --path ../smbios-mdr reviewers
{"reviewer": "bradleyb@fuzziesquirrel.com", "state": "REVIEWER"}
{"reviewer": "cbb7353e6d953ef360baf960c122346276c6e320@stwcx.xyz", "state": "REVIEWER"}
{"reviewer": "andrew@aj.id.au", "state": "CC"}
{"reviewer": "anoo@us.ibm.com", "state": "CC"}
{"reviewer": "gmills@linux.vnet.ibm.com", "state": "CC"}
{"reviewer": "jk@ozlabs.org", "state": "CC"}
{"reviewer": "joel@jms.id.au", "state": "CC"}
...
{"reviewer": "jonathan.doman@intel.com", "state": "REVIEWER"}
{"reviewer": "kuiying.wang@intel.com", "state": "REVIEWER"}
{"reviewer": "yugang.chen@linux.intel.com", "state": "REVIEWER"}
{"reviewer": "zhikui.ren@intel.com", "state": "REVIEWER"}
```

Change-Id: Idda5e344c1d061d1ceaef35b65d546b3b679b382
Signed-off-by: Patrick Williams <cbb7353e6d953ef360baf960c122346276c6e320@stwcx.xyz>

openbmc/openbmc-build-scripts,openbmc/openbmc-build-scripts