Rework/Improve the Slurmdbd related API

[tazend]

General

• Put into seperate package: slurmdbd
• Have a central class to manage opening/closing Slurmdbd connections

Portions that need a rework or new/improved Functionality

• Implement handling Users/Accounts/Associations (List/Modify/Delete/Add)
• Implement handling WCKeys (List/Modify/Delete/Add)
• Improve listing Events
• Improve listing Transactions
• Improve listing Reservations
• Improve/Implement Cluster functions (List/Modify/Delete/Add)
• Improve/Implement QOS functions (List/Modify/Delete/Add)
• Implement fetching slurmdbd config
• Implement Archive functionality
• Implement listing TRES
• Implement listing Runaway Jobs