Epic
As a user or app using Jira links, I want provide more details to the link relation, so that I can understand the reason for a relation much better.

Business Benefit

1. Understand background of an link relation as context
2. Extend app functionality by directly issue related information instead of shadow background table information
3. Ability to sort/filter and search for related issues

Acceptance Criteria

1. Provide custom fields to link relation for user update
2. Provide properties to link relation to allow apps to maintain user-hidden details
3. Search/Filter capability for fields and properties
4. Read/write permissions for fields