Improve FileIO

[palaviv]

The following changes are part of the efforts to enable .pyc files.
This change allow the following:

• Receive open fd descriptor as name parameter.
• Accept ByteArray as input to write.
• Ignore chars after first char in mode.

[codecov-io]

Codecov Report

Merging #1062 into master will increase coverage by 0.02%.
The diff coverage is 27.9%.

@@            Coverage Diff             @@
##           master    #1062      +/-   ##
==========================================
+ Coverage   64.65%   64.68%   +0.02%     
==========================================
  Files         101      101              
  Lines       18305    18307       +2     
  Branches     4042     4037       -5     
==========================================
+ Hits        11836    11842       +6     
- Misses       3688     3690       +2     
+ Partials     2781     2775       -6

Impacted Files	Coverage Δ
vm/src/stdlib/io.rs	65.3% <27.9%> (+0.97%)	⬆️
vm/src/builtins.rs	70.01% <0%> (+0.05%)	⬆️
vm/src/exceptions.rs	48.14% <0%> (+0.23%)	⬆️

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