Mask Subscription Key in GLPI Interface

[Pieurre]

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Contribution description

Description:
Currently, the subscription key in GLPI is displayed in plain text, which poses a security risk. To enhance security and prevent accidental disclosure, the key should be masked (e.g., replaced with asterisks) in the UI, with an option to reveal it when needed.

This improvement would help protect sensitive information and align with best security practices.

Steps to reproduce:

Navigate to the subscription settings in GLPI.
Observe that the subscription key is fully visible.
Expected behavior:

The subscription key should be masked by default.
A "Show/Hide" button should be available to reveal the key when necessary.
GLPI version: [Specify version]
Additional context: This change would improve security without impacting functionality.