[OAS] Support tags

[jloleysens]

Summary

Close #183935
Close #182649

Test

1. Start Kibana + ES
2. Add a tag like oas-tag:foo to a route under options.tags
3. Generate and view OAS using command like curl -suelastic:changeme http://localhost:5601/api/oas\?pathStartsWith\=/api/status | jq

Should contain (note addition of "global" tags object):

  "paths": {
    "/api/status": {
      "get": {
        "summary": "Get Kibana's current status.",
        "tags": [
          "foo"
        ],
  ...
  "tags": [{ "name": "foo" }],

[elasticmachine]

Pinging @elastic/kibana-core (Team:Core)

[pgayvallet]

LGTM

[jloleysens]

@elasticmachine merge upstream

[kibana-ci]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: f548010

Failed CI Steps

Metrics [docs]

Unknown metric groups

ESLint disabled line counts

id	before	after	diff
@kbn/router-to-openapispec	0	1	+1

Total ESLint disabled count

id	before	after	diff
@kbn/router-to-openapispec	0	1	+1

History

• 💔 Build #213614 failed efabb4e
• 💔 Build #213591 failed df65c92
• 💔 Build #213553 failed 116b1a6
• 💔 Build #213548 failed f3f6c4b
• 💔 Build #213109 failed 461e8ce
• 💛 Build #212867 was flaky c9fbae7

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

cc @jloleysens

[lcawl]

Tested output and it passes linting rules. LGTM!