Drop some legacy browser code

[cconard96]

Checklist before requesting a review

• I have read the CONTRIBUTING document.
• I have performed a self-review of my code.

Description

• Drop some IE support which has not been a supported browser for GLPI since 9.5.
• Drop use of Pragma header which has been replaced by Cache-Control. Pragma only has use in systems that do not support the HTTP/1.1 standard which was released in 1997.
• Remove -webkit-box-shadow and -moz-box-shadow in favor of box-shadow as it is part of the CSS baseline since 2015.
• Remove -webkit-appearance in favor of appearance as it is part of the CSS baseline since 2022.
• Remove all -ms-* CSS properties as they are for IE and pre-Chromium Edge browsers which have not been supported by GLPI for several years.
• Remove -moz-user-select in favor of user-select as it has been supported by Firefox since late 2019. The -webkit-user-select property was left in place as Safari still does not support the standard version.
• Remove -*-linear-gradient() in favor of linear-gradient() as it is part of the CSS baseline since 2022.

[trasher]

Seems OK to me, I guess it could target 11.0/bugfixes

[cedric-anne]

I am pretty sure that PHP automatically sends this header when a session is started. This should be double checked.

[trasher]

I guess all header_remove could be kept

[cconard96]

I didn't realize that and thought the comments were old and referring to something GLPI did when it started the session. Indeed the default cache limiter for sessions is "nocache" and this specific strategy sends the Pragma header.

However, if the Cache-Control header is present, all modern systems should use that and ignore any Pragma header.