Summary
At the moment WT_SESSION::alter is disabled here https://github.com/wiredtiger/wiredtiger/blob/9823f16b935907748705389093fb29775c444498/src/schema/schema_worker.c#L56 We need to enable the API and add missing support for tiered storage.

Acceptance Criteria (Definition of Done)
Most of the tiered scenarios in "test_alterXX.py" tests are skipped in "TieredConfigMixin.alter(self, uri, alter_param)" wrapper method. When the support is added the wrapper method should be removed and all the tests should call "session.alter()" directly.