feat: make plugin CSP compliant - #183

Declare the plugin compatible with the Content Security Policy sent by GLPI.
Searches for inline event handlers, javascript: URLs, <script> tags printed from PHP or created from JavaScript, on_change and on* option keys and deprecated confirmation helpers returned no hit in the plugin code, so only 'csp_compliant' => true is added to plugin_version_oauthimap().

Blocked by

• Add content security policy glpi-project/glpi#26020 (CSP) and its 11.0 backport are not released yet.
• The minimum GLPI version (PLUGIN_OAUTHIMAP_MIN_GLPI) must be raised to the first CSP-enabled 11.0 release before merging. This PR does not change it.

Checklist before requesting a review

• I have performed a self-review of my code.
• I have added tests (when available) that prove my fix is effective or that my feature works.
• I have updated the CHANGELOG with a short functional description of the fix or new feature.
• This change requires a documentation update.

Description

• Declares the plugin compatible with the GLPI Content Security Policy, see the Blocked by section for the GLPI release dependency.

Manual test checklist

Keep the browser console open: a CSP violation is reported as Refused to execute inline event handler or Refused to execute inline script.

1. On a CSP-enabled GLPI, open each page and tab added by the plugin and use its forms and buttons: everything behaves as before.
2. The browser console shows no CSP violation on these pages.