feat(gnovm): add importer package

[thehowl]

Supersedes #1299

WIP

[codecov]

Codecov Report

Attention: Patch coverage is 68.58407% with 71 lines in your changes are missing coverage. Please review.

Project coverage is 49.17%. Comparing base (50bf659) to head (8afeacf).

Files	Patch %	Lines
gnovm/pkg/importer/match.go	79.55%	27 Missing and 10 partials ⚠️
gnovm/cmd/gno/test.go	0.00%	24 Missing ⚠️
gnovm/pkg/importer/importer.go	0.00%	4 Missing ⚠️
gnovm/cmd/gno/transpile.go	0.00%	3 Missing ⚠️
gnovm/pkg/importer/definitions.go	60.00%	1 Missing and 1 partial ⚠️
gnovm/pkg/gnomod/gnomod.go	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2201      +/-   ##
==========================================
+ Coverage   49.08%   49.17%   +0.08%     
==========================================
  Files         576      579       +3     
  Lines       77821    77804      -17     
==========================================
+ Hits        38199    38257      +58     
+ Misses      36528    36455      -73     
+ Partials     3094     3092       -2     

Flag	Coverage Δ
contribs/gnodev	24.18% <ø> (ø)
contribs/gnofaucet	15.31% <ø> (ø)
contribs/gnokeykc	0.00% <ø> (ø)
contribs/gnomd	0.00% <ø> (ø)
gno.land	61.62% <ø> (ø)
gnovm	42.47% <68.58%> (+0.24%)	⬆️
misc/autocounterd	0.00% <ø> (ø)
misc/genproto	0.00% <ø> (ø)
misc/genstd	73.90% <ø> (ø)
misc/goscan	0.00% <ø> (ø)
misc/logos	17.38% <ø> (ø)
misc/loop	0.00% <ø> (ø)
tm2	54.54% <ø> (-0.04%)	⬇️

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[thehowl]

@n0izn0iz given your work on the "alternative" gnopls what do you think about using that expertise and the work creating that package driver to continue the work of this PR?

The intention is to create a system to unify:

• How import paths and directory paths are specified, and to exactly what packages and gno files they refer to.
• Where gno files are expected to be (gnoroot/examples? local directory? GNOHOME/packages?)

This was the intention of the work I started here, but it's complex for me to work on it at the time being, so if you had capacity to take it up I would be very glad :)