fix(datetime): make sure the epoch is not larger than the maximum supported value

[lafirest]

A user sets a large timestamp by API to the banned feature, the value of this timestamp is out of the supported range and will crash the list API of the banned feature, and meanwhile, there is no clean_all API in this feature, thus the user can't delete the bad date.

There will be a series PRs to unify the emqx_datetime and emqx_calender

Fixes

Summary

🤖 Generated by Copilot at 526c61c

Export and implement epoch_to_rfc3339 functions in emqx_calendar module and improve emqx_datetime module to handle maximum epoch timestamp. These changes are for better compatibility and validation of date and time formats.

PR Checklist

Please convert it to a draft if any of the following conditions are not met. Reviewers may skip over until all the items are checked:

• Added tests for the changes
• Added property-based tests for code which performs user input validation
• Changed lines covered in coverage report
• Change log has been added to changes/(ce|ee)/(feat|perf|fix)-<PR-id>.en.md files
• For internal contributor: there is a jira ticket to track this change
• Created PR to emqx-docs if documentation update is required, or link to a follow-up jira ticket
• Schema changes are backward compatible

Checklist for CI (.github/workflows) changes

• If changed package build workflow, pass this action (manual trigger)
• Change log has been added to changes/ dir for user-facing artifacts update

[coveralls]

Pull Request Test Coverage Report for Build 5831278886

• 7 of 7 (100.0%) changed or added relevant lines in 1 file are covered.
• 27 unchanged lines in 13 files lost coverage.
• Overall coverage increased (+0.02%) to 81.365%

---

Files with Coverage Reduction	New Missed Lines	%
apps/emqx_bridge_gcp_pubsub/src/emqx_bridge_gcp_pubsub_client.erl	1	94.74%
apps/emqx_connector/src/emqx_connector_jwt_worker.erl	1	89.47%
apps/emqx_dashboard/src/emqx_dashboard_monitor.erl	1	66.21%
apps/emqx_gateway_mqttsn/src/emqx_mqttsn_channel.erl	1	73.78%
apps/emqx_gateway/src/emqx_gateway_utils.erl	1	86.49%
apps/emqx/src/emqx_banned.erl	1	89.55%
apps/emqx/src/emqx_connection.erl	1	83.47%
apps/emqx/src/emqx_logger_jsonfmt.erl	1	84.92%
apps/emqx_bridge_gcp_pubsub/src/emqx_bridge_gcp_pubsub_consumer_worker.erl	2	93.31%
apps/emqx_ft/src/emqx_ft_storage_fs.erl	2	83.58%

Totals
Change from base Build 5830810370:	0.02%
Covered Lines:	32231
Relevant Lines:	39613

---

💛 - Coveralls