feat: New APIs for search (#6564)

- Adding new API endpoints for search
- Migrations to add appropriate indexes

app/controllers/api/v1/accounts/search_controller.rb

@@ -0,0 +1,28 @@
+class Api::V1::Accounts::SearchController < Api::V1::Accounts::BaseController
+  def index
+    @result = search('all')
+  end
+
+  def conversations
+    @result = search('Conversation')
+  end
+
+  def contacts
+    @result = search('Contact')
+  end
+
+  def messages
+    @result = search('Message')
+  end
+
+  private
+
+  def search(search_type)
+    SearchService.new(
+      current_user: Current.user,
+      current_account: Current.account,
+      search_type: search_type,
+      params: params
+    ).perform
+  end
+end