feat(gnovm): add software floating point package

[thehowl]

Based on the runtime softfloat64.go file.

Still WIP, need to include it into the source code for the GnoVM.

Contributors' checklist...

• Added new tests, or not needed, or not feasible
• Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory
• Updated the official documentation or not needed
• No breaking changes were made, or a BREAKING CHANGE: xxx message was included in the description
• Added references to related issues and PRs
• Provided any useful hints for running manual tests
• Added new benchmarks to generated graphs, if any. More info here.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 60.89%. Comparing base (1e27785) to head (bb0beb5).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2863      +/-   ##
==========================================
- Coverage   60.91%   60.89%   -0.03%     
==========================================
  Files         564      564              
  Lines       75273    75273              
==========================================
- Hits        45856    45839      -17     
- Misses      26046    26061      +15     
- Partials     3371     3373       +2     

Flag	Coverage Δ
contribs/gnodev	60.65% <ø> (-0.82%)	⬇️
contribs/gnofaucet	14.46% <ø> (-0.86%)	⬇️
gno.land	67.17% <ø> (ø)
misc/genstd	80.54% <ø> (ø)
misc/logos	19.88% <ø> (ø)
tm2	62.00% <ø> (-0.09%)	⬇️

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