feat: Add hCaptcha for public forms (#4017)

- added hCaptcha based verification for chatwoot signups

Co-authored-by: Sojan <sojan@pepalo.com>

lib/chatwoot_captcha.rb

@@ -0,0 +1,25 @@
+class ChatwootCaptcha
+  def initialize(client_response)
+    @client_response = client_response
+    @server_key = GlobalConfigService.load('HCAPTCHA_SERVER_KEY', '')
+  end
+
+  def valid?
+    return true if @server_key.blank?
+    return false if @client_response.blank?
+
+    validate_client_response?
+  end
+
+  def validate_client_response?
+    response = HTTParty.post('https://hcaptcha.com/siteverify',
+                             body: {
+                               response: @client_response,
+                               secret: @server_key
+                             })
+
+    return unless response.success?
+
+    response.parsed_response['success']
+  end
+end