GEP2257 Duration parsing

[xtineskim]

Per GEP 2257, adding duration utils for implementing GEP2257 duration format

What type of PR is this?
/kind feature
(not sure if this is the right kind for this 😅 )

What this PR does / why we need it:
Per GEP 2257 Duration formatting's next step to graduation is implementing parsers. Helping out with this push to standard channel 👍
Which issue(s) this PR fixes:

Fixes #
Related PRs:

• Add gateway_api::Duration type to support GEP-2257 Durations kube-rs/gateway-api-rs#45
• Add utility functions to parse and format GEP-2257 Duration strings for Gateway API kubernetes-client/python#2261

Does this PR introduce a user-facing change?:

NONE

cc: @kflynn

[k8s-ci-robot]

@xtineskim: The label(s) kind/(not, kind/sure, kind/if, kind/this, kind/is, kind/the, kind/right, kind/kind, kind/for, kind/this, kind/😅, kind/) cannot be applied, because the repository doesn't have them.

In response to this:

Per GEP 2257, adding duration utils for implementing GEP2257 duration format

What type of PR is this?
/kind feature (not sure if this is the right kind for this 😅 )

What this PR does / why we need it:
Per GEP 2257 Duration formatting's next step to graduation is implementing parsers. Helping out with this push to standard channel 👍
Which issue(s) this PR fixes:

Fixes #

Does this PR introduce a user-facing change?:

NONE

cc: @kflynn

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[kflynn]

So first, many many many thanks for volunteering to write these, @xtineskim! 🙏 🙏 😁 I really appreciate it and it's lovely to see this arrive with comments and tests and everything!

I've left comments which are mostly pretty small things and, honestly, have been informed by writing the Rust version of this, and I'm going to comment rather than approve just to make sure we get other eyes on the FormatDuration function. Many thanks again!! 🙂

[youngnick]

/approve

Nice work!

[kflynn]

I have a couple of minor comments, and I think I agree with @robscott about making all the formatters look roughly the same. Thanks for sticking with this!! 🙂

[robscott]

Thanks @xtineskim!

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: robscott, xtineskim, youngnick

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