This is a consolidation effort, avoiding usage
of naked strings in codebase. Whenever possible
use constants which can be repurposed elsewhere.
This also fixes `goconst ./...` reported issues.
* Filter lock info based on bucket, prefix and time since lock was held
* Implement list and clear locks REST API
* madmin: Add list and clear locks API
* locks: Clear locks matching bucket, prefix, relTime.
* Gather lock information across nodes for both list and clear locks admin REST API.
* docs: Add lock API to management APIs
