feat(core): update clock skew detection threshold and configs

[siddsriv]

Issue

Internal JS-7004

Description

Some updates for clock skew/retry behavior:

• detection threshold changes to 4 mins from 5 mins
• NTP midpoint formula for calculation of candidate skew
• Age header guard: discard skew candidate if response has an Age header
• Elapsed guard: discard skew candidate if round-trip exceeds 15 minutes
• new config option disableClockSkewCorrection

Note that disableClockSkewCorrection config resolver lives in httpAuthSchemes/aws_sdk/ (alongside the signer that consumes it) rather than a new submodule, following the NODE_AUTH_SCHEME_PREFERENCE_OPTIONS pattern, and because I want to keep this PR focused on the update. Adding a new submodule for this config would have some extra overhead.

smithy-ts Change: smithy-lang/smithy-typescript#2145

Testing

unit/integ testing

Checklist

• If the PR is a feature, add integration tests (*.integ.spec.ts) or E2E tests.
  • It's not a feature.
• My E2E tests are resilient to concurrent i/o.
  • I didn't write any E2E tests.
• I added access level annotations e.g. @public, @internal tags and enabled doc generation on the package. Remember that access level annotations go below the description, not above.
  • I didn't add any public functions.
• Streams - how do they work?? My WebStream readers/locks are properly lifecycled. Node.js stream backpressure is handled. Error handling.
  • No streams here.

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