feat: Add the ability to change the agent availability status (#6855)

* Add the option change agent availability

* Remove callout

* Move `AVAILABILITY_STATUS_KEYS` to constants

* Update app/javascript/dashboard/i18n/locale/en/agentMgmt.json

Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>

---------

Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>

app/javascript/dashboard/i18n/locale/en/agentMgmt.json

@@ -33,6 +33,7 @@
           "PLACEHOLDER": "Please select a role",
           "ERROR": "Role is required"
         },
+
         "EMAIL": {
           "LABEL": "Email Address",
           "PLACEHOLDER": "Please enter an email address of the agent"
@@ -74,6 +75,11 @@
           "LABEL": "Email Address",
           "PLACEHOLDER": "Please enter an email address of the agent"
         },
+        "AGENT_AVAILABILITY": {
+          "LABEL": "Availability",
+          "PLACEHOLDER": "Please select an availability status",
+          "ERROR": "Availability is required"
+        },
         "SUBMIT": "Edit Agent"
       },
       "BUTTON_TEXT": "Edit",