Create openAPI spec

Create spec for this project based on the current Drupal endpoints here: https://eclipsefdn.github.io/openvsx-publisher-agreement-specs/#/paths/~1publisher_agreement/get

added Documentation MBO prioritymedium statetodo team:webdev labels

assigned to @zacharysabourin

mentioned in issue #1 (closed)

marked this issue as blocking #3 (closed)

added statewip label and removed statetodo label

mentioned in commit zacharysabourin/eclipse-openvsx-api@31a068f2

mentioned in merge request !2 (merged)

added statereview label and removed statewip label

mentioned in commit fda9b44f

closed with merge request !2 (merged)