CRUD UI for AbsenceType

Implementation
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1. civicrm/absence/type

• show the listing of all the absence types in the database with standard actions for 'Edit', 'Disable',''Delete'
• 'Add Absence Type' Button

2. On clicking Add Absence Type' Button, Form elements are as follows:

• Add a textbox for Title
• Add a checkbox for Allow Credits
• (SKIP) If above is true, show drop down for 'Credit Activity Type' listing all Absence Types
• Add a checkbox for Allow Debits
• (SKIP) If above is true, show drop down for 'Debit Activity Type' listing all Absence Types
• Add a checkbox for 'Is Active?'

3. PostProcess :
On save, the absence types are saved in 'civicrm_absence_type' table