Regenerate bindings, adjust wrapper, add CI workflow

[JKRhb]

This PR updates the bindings to tinydtls and makes adjustments to the wrapper implementation. It also adds a CI workflow, recompiling the binaries and running the tests with them.

[codecov-commenter]

Codecov Report

Merging #8 (fe4d9b3) into main (0f73724) will increase coverage by 0.43%.
The diff coverage is 84.61%.

❗ Current head fe4d9b3 differs from pull request most recent head 953bac6. Consider uploading reports for the commit 953bac6 to get more accurate results

@@            Coverage Diff             @@
##             main       #8      +/-   ##
==========================================
+ Coverage   74.43%   74.87%   +0.43%     
==========================================
  Files           9        9              
  Lines         579      581       +2     
==========================================
+ Hits          431      435       +4     
+ Misses        148      146       -2     

Impacted Files	Coverage Δ
lib/src/ffi/generated_bindings.dart	48.59% <33.33%> (-0.93%)	⬇️
lib/src/util.dart	60.52% <50.00%> (ø)
lib/src/client.dart	85.36% <100.00%> (ø)
lib/src/ecdsa_keys.dart	97.50% <100.00%> (ø)
lib/src/library.dart	65.51% <100.00%> (+13.79%)	⬆️
lib/src/server.dart	89.05% <100.00%> (ø)

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