feat: round ingress expiry

[krpeacock]

Description

In order to more effectively provide caching options in the boundary nodes, it is useful to limit the areas of randomness among cacheable query results. This feature will set expiries to 5 minutes, rounded down to the nearest minute.

Fixes # (issue)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration.

Checklist:

• My changes follow the guidelines in CONTRIBUTING.md.
• The title of this PR complies with Conventional Commits.
• I have edited the CHANGELOG accordingly.
• I have made corresponding changes to the documentation.

[github-actions]

size-limit report 📦

Path	Size
@dfinity/agent	88.4 KB (+0.02% 🔺)
@dfinity/candid	13.58 KB (0%)
@dfinity/principal	5.2 KB (0%)
@dfinity/auth-client	92.68 KB (-0.01% 🔽)
@dfinity/assets	90.81 KB (-0.01% 🔽)
@dfinity/identity	89.96 KB (-0.01% 🔽)
@dfinity/identity-secp256k1	233.63 KB (+0.01% 🔺)

[krpeacock]

Note: This change makes it easy to reproduce what would have been an edge case before. By rounding the expiry, it means that sequential update calls may return the same response if the agent's disableNonce option is set.

This is not yet the default, so the scope of this PR doesn't need to cover that