fix(gnovm): prevent assignment to non-assignable expressions

[omarsy]

closes: #2889

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

Attention: Patch coverage is 92.85714% with 2 lines in your changes missing coverage. Please review.

Project coverage is 63.12%. Comparing base (af05780) to head (fbc3bbe).
Report is 15 commits behind head on master.

Files with missing lines	Patch %	Lines
gnovm/pkg/gnolang/type_check.go	92.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2896      +/-   ##
==========================================
- Coverage   63.32%   63.12%   -0.21%     
==========================================
  Files         548      548              
  Lines       78511    80213    +1702     
==========================================
+ Hits        49719    50636     +917     
- Misses      25438    26171     +733     
- Partials     3354     3406      +52     

Flag	Coverage Δ
contribs/gnodev	60.57% <ø> (ø)
contribs/gnofaucet	15.77% <ø> (+0.94%)	⬆️
gno.land	67.18% <ø> (ø)
gnovm	67.90% <92.85%> (+0.02%)	⬆️
misc/genstd	79.72% <ø> (ø)
tm2	62.37% <ø> (-0.05%)	⬇️

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[ltzmaxwell]

should share some logic with this: #1946

[mvertes]

Looks ok to me.

[thehowl]

lgtm, @ltzmaxwell please do merge after you're satisfied with the feedback