tools: owners: support recursive OWNERS

Search for any OWNERS files anywhere in the repository, rather than
just at the root, and incorporate their information into the
review-set.

Tested: Modified meta-aspeed/recipes-bsp/u-boot/u-boot-aspeed.inc
and observed additional reviewers as expected.

```
$ tools/owners --path $(wd path lfopenbmc) reviewers
{"reviewer": "bradleyb@fuzziesquirrel.com", "state": "REVIEWER", "notify": "NONE", "notify_details": {"TO": {"accounts": ["bradleyb@fuzziesquirrel.com"]}}}
{"reviewer": "edtanous@google.com", "state": "REVIEWER", "notify": "NONE", "notify_details": {"TO": {"accounts": ["edtanous@google.com"]}}}
{"reviewer": "geissonator@yahoo.com", "state": "REVIEWER", "notify": "NONE", "notify_details": {"TO": {"accounts": ["geissonator@yahoo.com"]}}}
{"reviewer": "joel@jms.id.au", "state": "REVIEWER", "notify": "NONE", "notify_details": {"TO": {"accounts": ["joel@jms.id.au"]}}}
{"reviewer": "patrick@stwcx.xyz", "state": "REVIEWER", "notify": "NONE", "notify_details": {"TO": {"accounts": ["patrick@stwcx.xyz"]}}}
{"reviewer": "chiawei_wang@aspeedtech.com", "state": "CC", "notify": "NONE", "notify_details": {"TO": {"accounts": ["chiawei_wang@aspeedtech.com"]}}}
{"reviewer": "zweiss@equinix.com", "state": "CC", "notify": "NONE", "notify_details": {"TO": {"accounts": ["zweiss@equinix.com"]}}}
```

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I08775e3975897066d79c22ba38f0fdef364ed708
1 file changed