Add the new "Requires Plugins" header to the Wetu Importer plugin to indicate the Tour Operator plugin dependency

[ashleyshaw]

Add Plugin Dependency for Where To Importer Add-On

Description:
The Where To Importer add-on for the Tour Operator plugin should have a dependency check that ensures the core Tour Operator plugin is installed and activated before the Where To Importer can function properly.

Requirements:

• Implement a dependency check using the WP_Plugin_Dependencies class to verify that the Tour Operator plugin is installed and active.
• Display an admin notice if the Tour Operator plugin is not installed, informing the user that it is required for the Where To Importer to work.
• Prevent the activation of the Where To Importer if the Tour Operator plugin is not active.

Technical References:

• Utilize the WP_Plugin_Dependencies class to manage plugin dependencies and ensure proper plugin loading behavior.

Acceptance Criteria:

• When attempting to activate the Where To Importer, it should check if the Tour Operator plugin is installed and active using WP_Plugin_Dependencies.
• An informative admin notice should appear if the dependency is not met.
• The Where To Importer add-on should deactivate automatically if the Tour Operator plugin is missing or deactivated.