Consider syncing capability checks

[tw2113]

We check for manage_options for the admin screen, but install_plugins for the actual action of running the switching.

Perhaps make install_plugins the requirement to even see the admin screen?

Original issue:
https://wordpress.org/support/topic/does-not-respect-capabilities-canyou-please-fix-asap/#post-12748575

[sc0ttkclark]

• manage_options is used for the management menu page:

  taxonomy-switcher/Taxonomy_Switcher_UI.php

  Line 87 in 52b0fea

  $this->options_page = add_management_page( $this->admin_title, $this->admin_title, 'manage_options', $this->admin_slug, array(

• install_plugins is used for running the conversion:

  taxonomy-switcher/taxonomy-switcher.php

  Line 51 in 52b0fea

  || ! current_user_can( 'install_plugins' )

I suggest manage_options should be the capability used for both.