Drop IE11 support & no env access for Deno

[gfx]

• Assumes TextEncoder exists (AFAIK IE11 is the only engine that does not support TextEncoder as of 2023)
• DataView always throws RangeError for its out of bounds except for IE11

close #219

[codecov-commenter]

Codecov Report

Patch coverage: 96.42% and project coverage change: +0.17 🎉

Comparison is base (bd0db9c) 98.14% compared to head (f1f96e4) 98.31%.

❗ Current head f1f96e4 differs from pull request most recent head 2f07cec. Consider uploading reports for the commit 2f07cec to get more accurate results

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #221      +/-   ##
==========================================
+ Coverage   98.14%   98.31%   +0.17%     
==========================================
  Files          16       16              
  Lines         968      952      -16     
  Branches      206      193      -13     
==========================================
- Hits          950      936      -14     
+ Misses         18       16       -2     

Impacted Files	Coverage Δ
src/Decoder.ts	99.16% <85.71%> (-0.01%)	⬇️
src/Encoder.ts	97.94% <100.00%> (-0.06%)	⬇️
src/utils/utf8.ts	96.87% <100.00%> (+1.72%)	⬆️

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