feat(ee): Add SLA management UI (#8777)

Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>
Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>
Co-authored-by: Pranav <pranav@chatwoot.com>

config/features.yml

@@ -66,3 +66,6 @@
   enabled: false
 - name: inbox_view
   enabled: false
+- name: sla
+  enabled: false
+  premium: true