Standardize title as Administer in breadcrumbs and on main Administer page

[larssandergreen]

Overview

Just a little cleanup to standardize the name of the admin page.

Before

Breadcrumbs use "Administer", "Administration", "Administer CiviCRM" and "Admin" to refer to the same path.

Main administration page is titled "Administer CiviCRM".

After

All breadcrumbs and the title of the main admin page match the menu: "Administer".

Comments

There are also ~5 help texts that include "Administer CiviCRM", but I don't think it is worth forcing these all to be retranslated for such a minor change.

[civibot]

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[mlutfy]

Thank you @larssandergreen !