refactor: move `ValidatedInput` to the `Input` namespace #15460

Job	Run time
Setup PHP Version for Code Coverage	3s
Others (8.4) / Sanity Tests	1m 34s
Others (8.5) / Sanity Tests	1m 49s
Others (8.3) / Sanity Tests	1m 46s
Others (8.2) / Sanity Tests	3m 19s
CacheLive (8.4) / Cache Live Tests	1m 29s
CacheLive (8.5) / Cache Live Tests	1m 34s
CacheLive (8.2) / Cache Live Tests	1m 35s
CacheLive (8.3) / Cache Live Tests	1m 31s
SeparateProcess (8.2) / tests	1m 48s
SeparateProcess (8.4) / tests	2m 9s
SeparateProcess (8.3) / tests	2m 21s
DatabaseLive (8.4, SQLSRV, 8.0) / tests	5m 57s
DatabaseLive (8.3, MySQLi, 8.0) / tests	3m 48s
DatabaseLive (8.4, Postgre, 8.0) / tests	2m 9s
DatabaseLive (8.2, MySQLi, 8.0) / tests	5m 15s
DatabaseLive (8.5, Postgre, 8.0) / tests	1m 58s
SeparateProcess (8.5) / tests	2m 2s
DatabaseLive (8.3, SQLSRV, 8.0) / tests	5m 21s
DatabaseLive (8.4, OCI8, 8.0) / tests	7m 50s
DatabaseLive (8.2, OCI8, 8.0) / tests	8m 44s
DatabaseLive (8.2, SQLSRV, 8.0) / tests	6m 45s
DatabaseLive (8.5, MySQLi, 8.0) / tests	4m 8s
DatabaseLive (8.3, OCI8, 8.0) / tests	7m 54s
DatabaseLive (8.2, Postgre, 8.0) / tests	2m 48s
DatabaseLive (8.3, SQLite3, 8.0) / tests	1m 11s
DatabaseLive (8.4, SQLite3, 8.0) / tests	1m 26s
DatabaseLive (8.3, Postgre, 8.0) / tests	1m 44s
DatabaseLive (8.2, SQLite3, 8.0) / tests	2m 28s
DatabaseLive (8.5, SQLSRV, 8.0) / tests	5m 2s
DatabaseLive (8.5, OCI8, 8.0) / tests	8m 9s
DatabaseLive (8.4, MySQLi, 8.0) / tests	4m 0s
DatabaseLive (8.5, SQLite3, 8.0) / tests	1m 3s
DatabaseLive (8.2, MySQLi, 5.7) / tests	3m 19s
Upload coverage results to Coveralls / coveralls	42s
	1h 54m 41s

Provide feedback