4.0.3 - Info section and minor fixes

[balexey88]

• NEW - added Info section to the Status tab on the Settings page, which contains the system info and the ability to copy report to clipboard.
• ENHANCEMENT - added Documentation link on the Plugins page.
• ENHANCEMENT - added Addons link on the Plugins page.
• ENHANCEMENT - added Documentation link on the Settings page.
• FIX - fixed Settings shortcut on the Plugins page.
• FIX - in multisite network, do not show Data Optimization on the Network Admin Page.
• FIX - properly set Content Disposition fields for media objects.
• FIX - properly use Cache Control setting for media objects.
• FIX - fixed Creation of dynamic property PHP deprecation notice.
• FIX - fixed Cannot use ::class with dynamic class name PHP warning.
• FIX - avoid PHP warning when unable to get file path in Stateless mode 728.
• FIX - fixed links to the constants documentation.