add CODEOWNERS file to all repos in OpenSearch

[CEHENKLE]

Meta issue to track adding CODEOWNERS files to all repos in the OpenSearch-project.

Recently a vulnerability was discovered for github that would allow branch protection rules to be ignored. We have already mitigated it by moving to 2 PRs, but the other way to mitigate is to add a codeowner file. Adding a code owner file will allow us to go back to 1 PR if we choose to do so.

More information about codeowners and branch protection rules...

• Add support for codeowners to repo data-prepper#578
• Add support for codeowners to repo reporting#227
• Add codeowner support for repo dashboards-notebooks#99
• Add support for codeowners to repo anomaly-detection#318
• Add codeowners support to repo anomaly-detection-dashboards-plugin#148
• Add codeowners support to repo asynchronous-search#64
• Adding Codeowners file opensearch-dsl-py#33
• Add codeowners support for repo common-utils#96
• adding CODEOWNERS file alerting-dashboards-plugin#150
• Adding a codeowners file. alerting#235
• Add support for codeowners to repo ml-commons#85
• Add support for codeowners to repo logstash-output-opensearch#93
• Add support for codeowners to repo k-NN#206
• Add support for codeowners to repo job-scheduler#100
• Add support for codeowners to repo index-management-dashboards-plugin#131
• Add support for codeowners to repo index-management#195
• Add support for codeowners to repo geospatial#10
• Add support for codeowners to repo documentation-website#264
• Add support for codeowners to repo data-prepper#578
• Add support for codeowners to repo OpenSearch-Dashboards#935
• Add support for codeowners to repo opensearch-cli#35
• Add support for codeowners to repo observability#244
• Add support for codeowners to repo sql#286
• Add support for codeowners to repo security-dashboards-plugin#861
• Add support for codeowners to repo project-website-search#35
• Add support for codeowners to repo project-website#477
• Add support for codeowners to repo piped-processing-language#13
• Add support for codeowners to repo perftop#28
• Add support for codeowners to repo performance-analyzer-rca#90
• Add support for codeowners to repo performance-analyzer#90
• Add support for codeowners to repo opensearch-plugins#104
• https://github.com/opensearch-project/opensearch-infra/pull/133
• Add support for codeowners to repo opensearch-devops#79
• Add support for codeowners to repo opensearch-dashboards-test-library#8
• Add support for codeowners to repo helm-charts#138
• Add support for codeowners to repo ansible-playbook#14
• Add support for codeowners to repo opensearch-dashboards-functional-test#26
• https://github.com/opensearch-project/opensearch-transport-net/pull/1
• Adding initial commit of CODEOWNERS file opensearch-net-abstractions#2