feat: Ability to specify the authentication type for imap server (#12306)

# Pull Request Template

## Description

This PR adds IMAP authentication mechanism selection to Chatwoot's email
inbox configuration. Users can now choose between 'plain', 'login', and
'cram-md5' authentication methods when configuring IMAP settings,
providing flexibility for different email providers that require
specific authentication types.

https://github.com/chatwoot/chatwoot/issues/8867

The implementation includes:
- Frontend dropdown with numeric keys (1, 2, 3) matching SMTP auth style
- Backend API validation for allowed authentication mechanisms
- Consistent 'cram-md5' format throughout the codebase
- Updated IMAP service to handle different auth types properly

This feature maintains consistency with existing SMTP authentication
options and follows the established UI/UX patterns in the application.

## Type of change

Please delete options that are not relevant.

- [x] New feature (non-breaking change which adds functionality)
- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] Breaking change (fix or feature that would cause existing
functionality not to work as expected)
- [ ] This change requires a documentation update

## How Has This Been Tested?

### Manual Testing:
- Tested in Docker environment
- Verified IMAP auth dropdown appears in inbox settings
- Confirmed all three auth mechanisms (plain, login, cram-md5) can be
selected and saved
- Tested API validation by attempting to save invalid auth mechanisms

### Automated Testing:
- Updated existing IMAP service tests to use consistent lowercase values
- Updated API controller tests for authentication parameter handling
- All tests pass locally with the new changes

### Test Configuration:
- Tested with both new and existing inbox configurations

## Checklist:

- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [x] I have commented on my code, particularly in hard-to-understand
areas
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [x] Any dependent changes have been merged and published in downstream
modules

## Additional Notes

- This feature is backward compatible and doesn't break existing IMAP
configurations
- The 'cram-md5' format is used consistently throughout (UI, API,
storage, services)
- Net::IMAP compatibility is maintained by converting to 'CRAM-MD5'
internally
- Follows the same pattern established by SMTP authentication
configuration

---------

Co-authored-by: João Santos <joao.santos@madigital.eu>
Co-authored-by: Sony Mathew <sony@chatwoot.com>

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

@@ -1011,7 +1011,8 @@
         "LABEL": "Password",
         "PLACE_HOLDER": "Password"
       },
-      "ENABLE_SSL": "Enable SSL"
+      "ENABLE_SSL": "Enable SSL",
+      "AUTH_MECHANISM": "Authentication"
     },
     "MICROSOFT": {
       "TITLE": "Microsoft",

app/javascript/dashboard/routes/dashboard/settings/inbox/ImapSettings.vue

@@ -5,11 +5,13 @@ import SettingsFieldSection from 'dashboard/components-next/Settings/SettingsFie
 import { useVuelidate } from '@vuelidate/core';
 import { required, minLength } from '@vuelidate/validators';
 import NextButton from 'dashboard/components-next/button/Button.vue';
+import SingleSelectDropdown from './components/SingleSelectDropdown.vue';
 
 export default {
   components: {
     SettingsFieldSection,
     NextButton,
+    SingleSelectDropdown,
   },
   props: {
     inbox: {
@@ -28,6 +30,12 @@ export default {
       login: '',
       password: '',
       isSSLEnabled: true,
+      authMechanism: 'plain',
+      authMechanisms: [
+        { key: 1, value: 'plain' },
+        { key: 2, value: 'login' },
+        { key: 3, value: 'cram-md5' },
+      ],
     };
   },
   validations: {
@@ -56,6 +64,7 @@ export default {
         imap_login,
         imap_password,
         imap_enable_ssl,
+        imap_authentication,
       } = this.inbox;
       this.isIMAPEnabled = imap_enabled;
       this.address = imap_address;
@@ -63,6 +72,7 @@ export default {
       this.login = imap_login;
       this.password = imap_password;
       this.isSSLEnabled = imap_enable_ssl;
+      this.authMechanism = imap_authentication || 'plain';
     },
     async updateInbox() {
       try {
@@ -77,6 +87,7 @@ export default {
             imap_login: this.login,
             imap_password: this.password,
             imap_enable_ssl: this.isSSLEnabled,
+            imap_authentication: this.authMechanism,
           },
         };
 
@@ -90,6 +101,9 @@ export default {
         useAlert(error.message);
       }
     },
+    handleAuthMechanismChange(mode) {
+      this.authMechanism = mode;
+    },
   },
 };
 </script>
@@ -155,6 +169,13 @@ export default {
           />
           {{ $t('INBOX_MGMT.IMAP.ENABLE_SSL') }}
         </label>
+        <SingleSelectDropdown
+          class="w-full"
+          :label="$t('INBOX_MGMT.IMAP.AUTH_MECHANISM')"
+          :selected="authMechanism"
+          :options="authMechanisms"
+          :action="handleAuthMechanismChange"
+        />
       </div>
       <NextButton
         type="submit"