bugfix #5218: de/encode custom state using base16

[div5yesh]

Issue #, if available: #5218

Description of changes:

• encode custom state using base16 to preserve state from Cognito's URI encoding.
• add base16 encoding/decoding util functions to aws-amplify/core.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

Merging #6851 into main will decrease coverage by 0.12%.
The diff coverage is 77.04%.

@@            Coverage Diff             @@
##             main    #6851      +/-   ##
==========================================
- Coverage   73.48%   73.35%   -0.13%     
==========================================
  Files         205      213       +8     
  Lines       12621    13153     +532     
  Branches     2460     2566     +106     
==========================================
+ Hits         9275     9649     +374     
- Misses       3157     3310     +153     
- Partials      189      194       +5     

Impacted Files	Coverage Δ
packages/api-graphql/src/types/index.ts	100.00% <ø> (ø)
packages/datastore/__tests__/schema.ts	100.00% <ø> (ø)
packages/datastore/src/storage/storage.ts	71.66% <ø> (ø)
packages/datastore/src/sync/outbox.ts	24.00% <0.00%> (-0.49%)	⬇️
packages/datastore/src/sync/processors/mutation.ts	13.19% <0.00%> (ø)
...rc/Providers/AmazonAIConvertPredictionsProvider.ts	61.01% <ø> (ø)
...pubsub/src/Providers/AWSAppSyncRealTimeProvider.ts	18.37% <0.00%> (-0.17%)	⬇️
packages/pushnotification/src/PushNotification.ts	51.72% <ø> (ø)
packages/datastore/src/sync/index.ts	15.41% <9.09%> (-0.04%)	⬇️
packages/datastore/src/sync/processors/sync.ts	16.66% <18.18%> (-0.44%)	⬇️
... and 64 more

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[ericclemmons]

This is looking great @div5yesh! I'm ready to approve, but would want to see a couple tests validating this since we ran into interesting behavior.

[ericclemmons]

This looks good!

The only concern I have is if this patch release will break existing IE 11 apps due to the use of TextEncoder.

IE 11 usage requires a good deal of polyfills by customers today, so needing a polyfill won't be new, but I'd like to also avoid breaking their apps the next time they npm install.

If we're already using TextEncoder elsewhere, I think we're good! Otherwise, are we converting strings to streams differently? (This implementing looks like what we needed to re-use toHex/fromHex)

@elorzafe What are your thoughts?

[elorzafe]

Thanks @div5yesh ! 👍 🌮 🎉

[github-actions]

This pull request has been automatically locked since there hasn't been any recent activity after it was closed. Please open a new issue for related bugs.

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