Improve the performance of `WP_Image_Editor_Imagick::supports_mime_type()`

[joemcgill]

WP_Image_Editor_Imagick::supports_mime_type() is called whenever WordPress is choosing which image editor library to use via wp_image_editor_supports() > _wp_image_editor_choose().

To see if the current server's version of ImageMagick supports a specific mime type, that method calls Imagick::queryFormats(), which can take a long time to run.

In the editor, wp_plupload_default_settings() makes triggers this code path to see if modern formats like WebP and AVIF are supported, which leads to a slower editor load time.

Since these supports values rarely change except for when changing hosting environments, we can cache these supports values for faster lookups.

Trac ticket: https://core.trac.wordpress.org/ticket/61532