Allow users to specify a time zone when creating schedules and configuring row-level TTL

It’s difficult for users to create consistent and predictable schedules and jobs when managing applications and their clusters within a single timezone. There are use cases where the exact time for when jobs, such as Schedules and Row-level TTL, execute is critical.

CockroachDB should make it simpler for end users to create and manage their jobs by allowing them to specify a timezone other than UTC.

Examples:

```
CREATE SCHEDULE users_rides_nightly FOR CHANGEFEED
INTO 'external://kafka-sink'
WITH format=csv
RECURRING '1 0 * * *'
WITH SCHEDULE OPTIONS first_run=now,
on_execution_failure=retry,
on_previous_running=skip
cron_tz = 'America/New_York';
```

```
CREATE TABLE public.events (
id UUID NOT NULL DEFAULT gen_random_uuid(),
description STRING NULL,
inserted_at TIMESTAMP NULL DEFAULT current_timestamp():::TIMESTAMP,
crdb_internal_expiration TIMESTAMPTZ NOT VISIBLE NOT NULL DEFAULT current_timestamp():::TIMESTAMPTZ + '3 mons':::INTERVAL ON UPDATE current_timestamp():::TIMESTAMPTZ + '3 mons':::INTERVAL,
CONSTRAINT events_pkey PRIMARY KEY (id ASC)
) WITH (ttl = 'on', ttl_expire_after = '3 mons':::INTERVAL, ttl_job_cron = '@hourly', cron_tz = 'America/New_York')

```

Jira issue: CRDB-30648