fix(demo-ui): demo UI unicode support

[dougtoppin]

Issue #, if available:
#416 Add unicode support to demo-ui to enable the use of keys containing unicode characters

This was an issue discovered by @batica81 where the demo-ui component of SIH did not support image keys containing unicode characters. The initial suggested fix included the use of a deprecated function.
The fixes contained in this PR were suggested by @fisenkodv did not use the deprecated function and tested successfully.

While testing, it was discovered that the use of watermark (overlay) images also did not support unicode characters in the backend which has been resolved in this PR.

Description of changes:

• scripts (front-end) encode key in request using encodeURIComponent
• image-request (backend) decode key using decodeURIComponent when request received
• image-handler (backend) decode key for watermark

Tested using combinations of keys with both ascii and unicode characters for both image and watermark keys.

Example test request bodies:

• unicode key (sharp style after base64 -d):

  {"bucket":"test-bucket","key":"Västerås.jpeg","edits":{"contentModeration":{"minConfidence":90,"blur":100,"moderationLabels":["Gambling"]}}}

• ascii key, unicode watermark (thumbor style):
  • https://cloudfront/filters:watermark(test-bucket,Va%CC%88stera%CC%8As.jpeg,50,50,0,25,50)/image.jpg
• unicode key. unicode watermark:
  • https://cloudfront/filters:watermark(test-bucket,Va%CC%88stera%CC%8As.jpeg,50,50,0,25,50)/čćšđ_unicode_test.jpg

Checklist

• 👋 I have run the unit tests, and all unit tests have passed.
• ⚠️ This pull request might incur a breaking change.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[fisenkodv]

Looks good to me

[hearde]

Is there a way to test this?

[dougtoppin]

@hearde My testing was to deploy the stack, copy an image to a unicode name for both the key and watermark and try various tests using different combinations. That was using both the demo-ui and api for various tests.
Supporting regression tests in the repo is on our backlog and will include the demo-ui. We also have updating the demo-ui in the backlog.