oauth2: Add default expiry for RFC compliance

[phlax]

Currently this filter does not work with Github - which would seem like one of the most likely use cases

This is a revival of #14625

Should fix #14542

Unblocks #31534

Commit Message:
Additional Description:
Risk Level:
Testing:
Docs Changes:
Release Notes:
Platform Specific Features:
[Optional Runtime guard:]
[Optional Fixes #Issue]
[Optional Fixes commit #PR or SHA]
[Optional Deprecated:]
[Optional API Considerations:]

[repokitteh-read-only]

CC @envoyproxy/api-shepherds: Your approval is needed for changes made to (api/envoy/|docs/root/api-docs/).
envoyproxy/api-shepherds assignee is @adisuissa
CC @envoyproxy/api-watchers: FYI only for changes made to (api/envoy/|docs/root/api-docs/).

🐱

Caused by: #31499 was opened by phlax.

see: more, trace.

[phlax]

cc @terorie @williamsfu99

[phlax]

/docs

[repokitteh-read-only]

Docs for this Pull Request will be rendered here:

https://storage.googleapis.com/envoy-pr/31499/docs/index.html

The docs are (re-)rendered each time the CI envoy-presubmit (precheck docs) job completes.

🐱

Caused by: a #31499 (comment) was created by @phlax.

see: more, trace.

[phlax]

/retest

[phlax]

this appears to work as expected in local testing

[adisuissa]

Left a small API comment.
cc @derekargueta @mattklein123 oauth2 code-owners.

[adisuissa]

Thanks!
/lgtm api

Assigning Matt as codeowner.
/assign @mattklein123

[adisuissa]

LGTM, thanks!

Oh, I think it needs a release note as well.

[phlax]

apologies for fp - im rebasing on this pr so it was to avoid the merge commit, pr commits were not changed