Drop php 7.2 support from CiviCRM 5.58 (after 5.57 ESR)

Per previous efforts to drop PHP version support I propose we drop 7.2 in 5.58. This means people who want another 6 months can use the ESR. Usage numbers for php 7.2 (around 1k) are around the levels where we dropped previous versions & support is starting to get harder - see https://github.com/civicrm/civicrm-core/pull/24952