Improve error message for invalid public key

[SaveTheRbtz]

Description

This diff improves error message in the InvalidPublicKeyError to provide information on not only what but also why public key validation failed:

before:

invalid public key: [248, 71, ..., 3, 232]

after:

invalid public key: [248, 71, ..., 3, 232], err: input has incorrect ECDSA_P256 key size

---

• Targeted PR against master branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• Code follows the standards mentioned here
• Updated relevant documentation
• Re-reviewed Files changed in the Github PR explorer
• Added appropriate labels

[codecov]

Codecov Report

Merging #1665 (c89326d) into master (66eac2a) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1665      +/-   ##
==========================================
- Coverage   76.50%   76.50%   -0.01%     
==========================================
  Files         291      291              
  Lines       60995    60995              
==========================================
- Hits        46666    46663       -3     
- Misses      12719    12720       +1     
- Partials     1610     1612       +2     

Flag	Coverage Δ
unittests	76.50% <100.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
runtime/interpreter/errors.go	22.11% <100.00%> (ø)
runtime/sema/checker.go	90.33% <0.00%> (-0.12%)	⬇️
runtime/sema/type.go	88.94% <0.00%> (-0.08%)	⬇️
runtime/sema/simple_type.go	96.15% <0.00%> (+3.84%)	⬆️

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[turbolent]

The reason why the key is invalid to the error message is definitely very helpful! Thank you for adding this

Could you please improve the title of the PR, e.g. to "Improve error message for invalid public key", and follow the checklist that was in the PR template? e.g. add a label instead of prefixing the title.
See https://github.com/onflow/cadence/blob/master/.github/pull_request_template.md

Thank you!

[turbolent]

Also: Feel free to create a branch in / PR from the repo directly (It does not matter for this PR, but PRs from other repositories do not run the benchmarking / performance regression suite)

[turbolent]

Nice! First PR 👏 🎉